Accepted Manuscript Synthesis of 2,3-di- and 2,2,3-trisubstituted-3-methoxycarbonyl-γ-butyrolactones as potent antitumor agents Camille Le Floch, Erwan Le Gall, Stéphane Sengmany, Patrice Renevret, Eric Léonel, Thierry Martens, Thierry Cresteil PII:
S0223-5234(14)01002-2
DOI:
10.1016/j.ejmech.2014.10.074
Reference:
EJMECH 7482
To appear in:
European Journal of Medicinal Chemistry
Received Date: 17 February 2014 Revised Date:
23 October 2014
Accepted Date: 26 October 2014
Please cite this article as: C. Le Floch, E. Le Gall, S. Sengmany, P. Renevret, E. Léonel, T. Martens, T. Cresteil, Synthesis of 2,3-di- and 2,2,3-trisubstituted-3-methoxycarbonyl-γ-butyrolactones as potent antitumor agents, European Journal of Medicinal Chemistry (2014), doi: 10.1016/j.ejmech.2014.10.074. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Multicomponent synthesis of densely substituted paraconic acid analogs In vitro cytotoxicity evaluation of the compounds in human cancer cell lines Sub-micromolar activity of one of the tested compounds Determination of the mode of action using flow cytometry
AC C
EP
TE D
M AN U
SC
RI PT
Activation of the apoptotic cascade without prominent blockade of the cell cycle
ACCEPTED MANUSCRIPT
AC C
EP
TE D
M AN U
SC
RI PT
Graphical Abstract
ACCEPTED MANUSCRIPT
Synthesis of 2,3-di- and 2,2,3-trisubstituted-3-methoxycarbonyl-γγ-butyrolactones as potent antitumor agents Camille Le Flocha, Erwan Le Galla,*, Stéphane Sengmanya, Patrice Renevretb, Eric Léonela, Thierry Martens,a Thierry Cresteilc a
RI PT
Électrochimie et Synthèse Organique, Institut de Chimie et des Matériaux Paris-Est, UMR 7182 CNRS - Université Paris-Est Créteil, 2-8 rue Henri Dunant, 94320 Thiais, France b Plateforme Chromatographie Analytique et Préparative, Institut de Chimie et des Matériaux Paris-Est, UMR 7182 CNRS – Université Paris-Est Créteil,2-8 rue Henri Dunant, 94320 Thiais, France c Ciblothèque cellulaire, Institut de Chimie des Substances Naturelles, CNRS-UPR 2301, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France
SC
∗ Corresponding author. Tel.: +33-149781135; fax: +33-149781148; e-mail: [email protected]
Keywords: Lactones; Paraconic acid analogs; Multicomponent reaction; Biological evaluation; Cytotoxic activity.
M AN U
Abstract: Various 2,3-substituted γ-butyrolactones have been synthesized by three-component reaction of aryl bromides, dimethyl itaconate and carbonyl compounds. The in vitro cytotoxic activity of these products was evaluated against a representative panel of cancer cell lines (KB, HCT116, MCF7, MCF7R, PC3, SK-OV3, HL60 and HL60R). One compound (4x) displays a good anti-proliferative activity with IC50 in the sub-micromolar range. The mechanism of action has been investigated using flow cytometry. 1. Introduction
TE D
The γ-butyrolactone core is widely present in natural compounds possessing biological activities [1-6]. In this context, paraconic acids [7-12] (γ-butyrolactones bearing a carboxylic acid function at the position β to the carbonyl,
EP
see scheme 1), constitute an important group of γ-butyrolactones that not solely display antitumor and antibiotic activities, but also represent relevant building blocks for the synthesis of diverse pharmacologically active compounds [13-15]. Due to these attractive properties, their synthesis has been the subject of tremendous efforts in the past few years. However, although the preparation of these compounds has been described through several strategies [16-24], the straightforward synthesis of densely substituted γ-butyrolactones still represents a challenge, especially for structure-activity relationship (SAR) studies.
AC C
In this context, multicomponent reactions (MCRs) [25-33] are processes of high interest as they potentially provide structural complexity starting from simple and/or commercial reagents, thus enabling a straightforward access to molecular diversity. In recent papers, we highlighted the use of aryl halides as precursors of organometallic species, in multicomponent reactions [34]. Given the high functional tolerance displayed by these species, it was envisaged their utilization in multicomponent reactions providing diversely-substituted products and the further biological assessment of the newly constituted libraries of compounds. Therefore, we report herein the preparation of densely substituted paraconic acid analogues by a zinc-mediated, cobalt-catalyzed multicomponent reaction between aryl halides, carbonyl compounds and dimethyl itaconate and their evaluation as potent antitumor agents.
ACCEPTED MANUSCRIPT
2. Results and discussion 2.1. Chemistry
M AN U
SC
RI PT
The synthesis of densely-substituted paraconic acid analogs 4 was envisaged via a reductive three component coupling between a carbonyl compound 1, an aryl bromide 2 and dimethyl itaconate 3 (scheme 1) [35-36]. The reaction was anticipated to proceed via a conjugate addition/aldol reaction/cyclization domino reaction, whose initiation would be performed by the initial in situ generation of an arylmetal reagent (that would undergo the key conjugate addition onto itaconate, starting point of the cascade).
Scheme 1. Some natural paraconic acids and retrosynthetic approach to synthetic analogs The initial metallation of the aromatic bromide 2 was considered through the use of the Zn(0)/Co(II) system [37], which had already provided reliable results in multicomponent processes. Preliminary experiments revealed that the most convenient experimental conditions were the following: acetonitrile is used as a solvent, zinc dust as a reductive metal, CoBr2 as a catalyst and the aryl bromide, the aldehyde and dimethyl itaconate are stirred at 60°C for a few
TE D
hours [38]. These conditions allowed the synthesis of a representative set of diversely-substituted γ-butyrolactones. Results are reported in Table 1.
AC C
EP
Table 1. Synthesis of γ-butyrolactones 3.a
Entry
Carbonyl compound 1
Aryl bromide 2
Yield (%)b
Product
4a
64
2
4b
99
3
4c
54
4
4d
48
1
ACCEPTED MANUSCRIPT 4e
55c
6
4f
95
7
4g
44
8
O
Br
9
4h
71c
4i
33
SC
O
RI PT
5
4j
56
4k
98
4l
67
4m
78
4n
56
4o
96
16
4p
78
17
4q
73
18
4r
98c
M AN U
10
11
14
AC C
15
EP
13
TE D
12
ACCEPTED MANUSCRIPT O
Br
4s
42
20
4t
56
21
4u
49
19
RI PT
O
22
27
4w
82
SC
23
4v
4x
85
4y
60
4z
87c
4aa
54
4ab
52
4ac
41
30
4ad
22
31
4ae
23
32
4af
15c
33
4ag
46
M AN U
24
25
28
AC C
29
EP
27
TE D
26
ACCEPTED MANUSCRIPT 34
4ah
99
35
4ai
89
4aj
51
O O H3C
36
4ak
52
4al
66
SC
CO2Me
RI PT
F3C
14
37
38
4am
M AN U
39 a
Experiments were conducted with 20 mL of acetonitrile, 10 mmol of the carbonyl compound 1, 15 mmol of the aryl bromide 2, 7.9 g (50 mmol) of dimethyl itaconate 3, 3 g (46 mmol) of zinc dust, 0.44 g (2 mmol) of CoBr2, at 60°C for 1-3 h. b Isolated yield. c Reaction conducted at room temperature.
These results reveal that an important variety of functionalized aromatic aldehydes and halides is useable in the
TE D
process. Ketones also undergo the reaction to furnish 2,2,3,3-tetrasubstituted γ-butyrolactones (Table 1, entries 2339). It can be noted that cyclic ketones can also be employed in the process to give rise to the formation of spiranic compounds, albeit in far more limited yields (Table 1, entry 39). Under these general conditions, mixtures of diastereoisomers were obtained (in the form of racemic mixtures of enantiomers). Diastereoisomeric ratios were typically ranging from 80:20 to 60:40. Due to difficulties encountered in the separation of the diastereoisomers, the initial biological evaluation was carried out on well mastered mixtures (~ 50:50) of the diastereoisomers in order to both obtain reliable results and comparable scales of biological activities.
EP
2.2. Evaluation of the cytotoxic activities
AC C
The inhibition of cell proliferation/viability by these diversely functionalized molecules was evaluated in vitro against a panel of human cancer cell lines (KB (nasopharyngeal), HCT116 (colon), MCF7 (breast), and HL60 (leukemia)). Results are reported in Table 2. Table 2. Percentage of cell growth inhibition at 10 µM in DMSO. Entry
Compound
KB
HCT116
MCF7
1
4a
18±6
0±3
0±7
2
4b
12±2
0±10
0±13
3
4c
4±7
4±11
0±9
4
4d
39±8
14±2
5
4e
42±5
25±2
6
4f
19±11
7
4g
8
4h
9 10
HL60
Entry
Compound
KB
HCT116
MCF7
HL60
22±11
21
4u
32±4
0±5
0±6
29±8
19±2
22
4v
13±8
12±2
28±2
8±4
4±4
23
4w
6±5
9±5
13±9
22±1
11±5
34±4
24
4x
95±1
61±1
56±2
82±1
35±2
28±4
25
4y
5±7
14±5
16±3
30±1
4±3
0±4
15±7
26
4z
9±4
13±2
10±6
34±2
0±1
14±7
12±8
37±5
27
4aa
56±1
20±3
8±8
64±2
7±1
23±3
18±10
42±9
28
4ab
22±5
25±1
12±18
17±3
4i
0±17
18±4
11±5
18±6
29
4ac
11±5
28±3
21±7
30±4
4j
0±11
16±5
1±16
7±6
30
4ad
15±11
25±3
19±5
28±2
4ae 4±9 37±5 MANUSCRIPT 31 ACCEPTED
11
4k
33±2
12
4l
0±6
0±4
4±7
2±4
32
13
4m
25±8
10±1
15±4
14±4
33
14
4n
31±7
0±11
0±1
23±7
15
4o
2±5
7±2
17±2
27±1
16
4p
16 ± 12
24 ± 2
27 ± 6
17
4q
0±4
20±3
13±5
18
4r
6±7
19±3
12±9
19
4s
0±4
22±2
20
4t
0±16
13±5
21±7
22±4
20±4
21±2
4af
0±12
18±1
6±5
0±11
4ag
22±3
44±3
35±5
43±3
34
4ah
0±16
0±18
2±16
7±11
35
4ai
0±13
8±3
7±4
24±3
32 ± 1
36
4aj
34±1
14±3
14±3
20±1
10±6
37
4ak
38±5
30±6
46±3
52±1
22±3
38
4al
0±7
15±3
7±4
9±4
8±9
10±2
39
4am
7±13
0±3
1±10
4±2
3±11
0±6
RI PT
0±5
M AN U
SC
It can be noted that most molecules exhibit a low to moderate antiproliferative activity on both KB and HL60 cancer cell lines. With a bare phenyl at the 2 position (Table 2, entries 1-10), the presence of a CF3 group on the benzyl moiety provides increased activities, especially at the meta and ortho position (Table 2, entries 4-5). Although a 4-methoxybenzyl group at the 3 carbon does not result in increased activities (Table 2, entry 6) when a bare phenyl is present at the 2 carbon, it can be noted that some substantial enhancement of the cytotoxicity is observed when the phenyl group is substituted by a F or a CF3 (Table 2, entries 11 and 14). With a 2 carbon substituted by both a phenyl and a methyl group (Table 2, entries 23-26 and 30-37), a methoxy group located at the para position of the benzyl moiety provides the best results (Table 2, entry 27). Indeed, compound 4x, obtained from acetophenone, 4bromoanisole and dimethyl itaconate, exhibits an increased antiproliferative activity compared to the other products,
AC C
EP
TE D
with cellular growth inhibitions higher than 50% in the four cell lines at a concentration of 10 µM. The replacement of the CH3 group of 4x by a CF3 (Table 2, entry 27) or by a CH2CH3 (Table 2, entry 29) results in a moderate to important decrease of the cytotoxicity. The cytotoxicity also drops when the 4-methoxybenzyl group is replaced by a benzyl (Table 2, entry 28), indicating the crucial importance of the OMe substituent. Moreover, although a CF3 group on the benzyl group had provided increased activities when the 2 carbon was trisubstituted (Table 2, entries 4-5), no significant modification of the cytotoxicity is observed when the 2 carbon is quaternary (comparison of entry 23 and entries 30-32 of Table 2). It can also be noted that contrary to what is observed with some well known antitumor agents like steganacin [39] or combretastatin A-4 [40], which acts by initial binding to tubulin, polymethoxylated phenyl groups do not bring a notable improvement of biological activity, both with a trisubstituted (Table 2, entries 15-20) and a tetrasubstituted 2 carbon (Table 2, entries 34-35). The activity of the lead 4x seems to be linked to the presence of both Me and Ph at the 2 position. Indeed, the functionnalization of the phenyl by a CF3 group (Table 2, entry 37) also results in a slight decrease of the biological activity compared to a bare phenyl. Although the cytotoxicities are far more limited than with acetophenone as one of the starting compounds, it can be noted that aliphatic aldehydes can be used in the process to introduce an aliphatic side chain. This latter seems to promote a slight increasing of the cytotoxicity against MCF7 (Table 2, entry 22). On the contrary, compound 4al, exhibiting two Me groups at the 2 position and the more unusual spiranic compound 4am, obtained from a cyclic ketone, are characterized by a general lack of activity (Table 2, entries 38-39). A deeper investigation of the anti-proliferative activities of compound 4x was undergone. Therefore, the determination of the IC50 values was undertaken on KB (figure 1), HCT116 (data not shown), MCF7 (data not shown) and HL60 (data not shown) cancer cell lines. These experiments were carried out in duplicate. The minimum and maximum values of IC50 are indicated in Table 3.
Figure 1. Graphical determination of IC50 values. ACCEPTED
MANUSCRIPT
50
0.001
0.01
0.1
1
10
Concentration (µM)
Table 3. IC50 of compound 4x.
100
HCT116
MCF7
HL60
0.4 / 0.9
1.3 / 2.4
2.8 / 6.4
0.9 / 2.0
SC
KB
M AN U
IC50 min / max (µM)
RI PT
0
Cell growth inhibition (%)
100
Graph#1
As it can be observed from these results, IC50 values are very homogeneous and comprised in the 0.1-1 µM range. These promising results prompted us to undertake an extended evaluation of the cytotoxic activities of compound 4x. Therefore, this latter was assessed against an additional panel of cancer cell lines including, among others, multidrug resistant cell lines MCF7R and HL60R. Overall results are reported in Table 4. Table 4. Cellular growth inhibition percentage of compound 4x at 10 µM in DMSO. HCT116
95 ± 1
61 ± 1
MCF7
MCF7R
TE D
KB
56 ± 2
82 ± 1
HL60
HL60R
PC3
SK-OV3
82 ± 1
92 ± 2
68 ± 1
76 ± 1
These results confirm the potent in vitro activities of compound 4x against various cancer cell lines. The inhibition
AC C
EP
of the proliferation of PC3 (prostate) and SK-OV3 (ovary) cancer cell lines is significant at 10 µM with respective 68% and 76% inhibition of cellular growth. In addition, these results might indicate that compound 4x is not substrate of P-gp, since multidrug resistant cell lines MCF7R and HL60R are affected in the same fashion as their sensitive counterpart cell lines. 2.3. Mechanism of action
Apoptosis and necrosis are two distinct and redundant forms of cell death that can occur in response to chemical aggression. These two cellular processes feature different and complementary modes of action: apoptosis or programmed cell death is executed in animal cells via the activation of cellular proteases leading to the cleavage of chromatin into nucleosomal fragments [41], while necrosis involves the destruction of the plasma membrane leading to the release of cytosolic lactic dehydrogenase into the culture medium, used as the hallmark of necrosis. Among chemicals capable to promote necrosis, high doses of menadione generate high levels of intracellular reactive oxidant species inducing lethal oxidant stress [42]. At first, we evaluated the effect of compound 4x on the necrotic process.
Figure 2. Total LDH activity in HL60 cells (panel A) and in the supernatant of intact cells (panel B) treated for 48 h with ACCEPTED MANUSCRIPT reference compounds and compound 4x. Control cells received DMSO only (1% final volume) and positive control 50 µM menadione or 1 µM doxorubicin. Results are expressed as the percentage±SE of LDH activity presented in untreated cells.
B
SC
RI PT
A
M AN U
As displayed in figure 2A, after the complete lysis of cells with triton X100, the total LDH activity reflecting the total cell number was reduced and confirmed the antiproliferative activity of compound 4x. In intact cells treated with the reference compound doxorubicin and compound 4x (figure 2B), the membrane integrity was maintained and no release of cytosolic LDH was noticed, whereas 50 µM menadione produced as expected a marked release of LDH into the culture medium. This clearly indicated that compound 4x is not necrotic for cells.
EP
TE D
Cell death mechanism was next evaluated by FACS using two impermeant dies for intact cells, annexin and 7 AAD. The first event occurring during apoptosis is the externalization of phosphatidyl-choline from the inner membrane leaflet to the outer plasma membrane, followed by the secondary loss of membrane integrity during late apoptosis/necrosis. In intact cells, phosphatidyl-choline is inaccessible to annexin, as well as the DNA intercalator 7AAD cannot penetrate the nucleus. During early apoptosis, phosphatidyl-choline is externalized and becomes accessible to annexin whereas cells remained impermeable to 7-AAD. In late apoptosis the cell membrane integrity is lost allowing both annexin and 7-AAD to freely penetrate into the cell and tag their respective targets. Therefore, the effect of a 48 h exposure to the reference compound doxorubicin and to increasing doses of compound 4x was explored in HL60 cells. Doxorubicin elicited a massive entry of cells in the early apoptotic stage, as well as compound 4x did in a dose-dependent manner (Table 5). Therefore we can conclude that compound 4x primarily induces cell death through the activation of apoptosis.
AC C
Table 5. FACS analysis of apoptosis in HL60 cells treated for 48 h with compound 4x. Control cells received dmso only (1% final volume) and positive control 100 nM doxorubicin. Results are expressed as the percentage of cells in the different stages of apoptosis.
dmso
Dead cells %
Late apoptosis %
Intact cells %
Early apoptosis %
0.4
0.4
80.7
18.5
3.15
14.7
81.65
2 µM 0.35
0.65
61.45
37.65
5 µM 0.9
2.2
50.55
46.4
10 µM 1.65
4.25
40.7
53.35
doxo 100 nM 0.5 4x
It is assumed that caspase 3 is the terminal effector of the apoptotic cascade [43]: this protease is activated in cell undergoing apoptosis after processing of the inactive procaspase 3 into its catalytically active form, capable to cleave DEVD-AMC and release the fluorescent moiety. Therefore, HL60 cells were treated with compound 4x for 24 and 48 h and with the positive reference 100 nM doxorubicin. Activation of caspase 3 activity was enhanced as early as
24 h of treatment (data not shown) and ACCEPTED was maximal after 48 h (Figure 3) with a 4x concentration of 5 µM. So we MANUSCRIPT can conclude that compound 4x induced apoptosis in cells through the activation of the caspase cascade. Figure 3. Activation of caspase 3 in HL60 cells treated for 48 h with compound 4x and the positive control 100 nM doxorubicin. Results are expressed as the percentage±SE of caspase 3 activity presented in cells treated with dmso only. 800% 700% 600%
400% 300% 200% 100%
SC
4x 5µM
4x 2µM
4x 1µM
M AN U
Doxo
dmso
0%
4x 10µM
RI PT
500%
EP
TE D
In the last part of this study, the effect of compound 4x was tested on the cell cycle. Four phases are classically defined in mammalian cell cycle: in resting cells (G0/G1) 2n chromosomes are present, followed by DNA synthesis (S) to reach 4n chromosomes (G2) before mitosis and cell division (M). Some chemicals are known to stop the cell cycle at a specific step according to their target and mode of action. Therefore it is possible to get insight in the mode of action of anti-proliferative compound by an accurate determination of cell proportion in each cycle phase. Cells were treated with the positive reference or with increasing concentrations of compound 4x before the addition of a DNA marker. As shown in figure 4, the reference compound doxorubicin elicited a blockade of the cell cycle in phase G2/M. Compound 4x at a low concentration had the same albeit moderate and transient effect, together with a slight increase of the number of cells in an apoptotic situation (sub G1). The number of apoptotic cells increased in a dose-dependent manner with compound 4x, without prior augmentation of cells in G2/M. Therefore it is possible to conclude that 4x did not elicit a massive arrest of cell proliferation in a specific stage but actively promoted apoptosis.
AC C
Figure 4. Cell cycle analysis of HL60 cells treated with doxorubicin and compound 4x for 48 h. Results are the percentage of cells in the different cycle stages after staining with propidium iodide and FACS analysis.
DMSO
doxo 50 nM
4x 2 µM
4x 5 µM
4x 10 µM
23.0 36.3 23.4 ACCEPTED MANUSCRIPT
G0/G1
42.9
19.5
S Phase
45.0
32.5
24.0
25.6
29.7
G2/M
11.6
40.0
25.6
12.2
13.1
SubG1
0.5
4.5
14.1
38.9
37.7
RI PT
Finally, as biological activities are generally linked to stereochemical pattern, we envisaged to further assess the cytotoxicity of both diastereoisomers of the lead compound 4x, taken independently. Therefore, a delicate chromatographic separation of a reaction mixture of 4x was undergone and fortunately, we succeeded in the isolation of both diastereoisomers 4xA and 4xB, which were submitted to a cytotoxic evaluation on KB, HCT116, MCF7 and HL60 cells. Results are indicated in Table 6.
SC
Table 6. In vitro cytotoxicity profile of diastereoisomers 4xA and 4xB.a
Percentage of cell growth inhibition at 10 µM in DMSO
4xA
15±5
4xB
98±1
a
HCT116
MCF7
M AN U
KB
HL60
0±19
0±10
24±2
56±2
59±3
68±1
The stereochemistry of both diastereoisomers 4xA and 4xB had been obtained previously through X-Ray diffraction experiments, see ref. 36 for details.
3. Conclusion
TE D
As diastereoisomer 4xA does not possess significant biological activity compared to 4xB, which is far more active, these results clearly indicate that the activity of the ~50:50 mixture (so-called compound 4x, see Table 2, entry 24) is mostly due to the trans diastereoisomer 4xB.
AC C
EP
In summary, the multicomponent reaction reported herein provides a reliable access to a wide variety of diversely substituted paraconic acid analogs. The biological activity of this novel class of compounds was evaluated against a representative set of human cancer cell lines. One of the molecules proved to exhibit a promising inhibition of cellular growth with IC50 values generally below 10-5 M. Its mode of action strongly suggested an activation of the apoptotic cascade without prominent blockade of the cell cycle. 4. Experimental 4.1. General
All reactions were carried out under argon atmosphere. Reagents and solvents were obtained from commercial suppliers and used without further purification. Reactions were monitored by gas chromatography (GC) on a Varian 3300 chromatograph fitted with a DB1 capillary column (l = 5 m, Ø = 0.32 mm, df = 0.4 µm). Melting points (mp) were determined on a Büchi Melting Point B-545. Infrared spectra were recorded on a Bruker TENSOR 27 spectrometer and treated via OPUS software. NMR spectra were recorded in CDCl3 at 400 MHz (1H), 100 MHz (13C), and 376 MHz (19F) on a Bruker Avance II 400 spectrometer. Chemical shifts (δ) are reported in parts per million (ppm) relative to the residual solvent signal. Coupling constant values (J) are given in Hertz (Hz) and refer to apparent multiplicities, indicated as follows: s (singlet); d (doublet); t (triplet); q (quadruplet); m (multiplet); dd (doublet of doublets). NMR peak assignments were determined using a combination of DEPT, HMBC, HSQC,
COSY and NOESY experiments. FlashACCEPTED chromatographyMANUSCRIPT was performed on silica gel (Merck, 35-70 µm particles, + 550 mesh). Mass spectra were recorded in ESI mode on a Thermo Scientific ITQ 700 GC-MS spectrometer fitted with a CPSIL5CB/MS capillary column (l = 25 m, Ø = 0.25 mm, df = 0.12 µm). Elemental analyses were carried out by the microanalysis facility, ICSN Gif-sur-Yvette, France. High resolution mass spectra were obtained from the Mass Spectroscopy facility of the Institut de Chimie Organique et Analytique, Orléans, France. Biological assays were carried out by the Ciblothèque Cellulaire facility of the IMAGIF platform, ICSN Gif-sur-Yvette, France. 4.2. General procedure for the synthesis of γ-butyrolactones 4a-am
M AN U
4.3. Separation of diastereoisomers 4xA and 4xB
SC
RI PT
A dried 100 mL round bottom flask was flushed with argon and charged with acetonitrile (20 mL). Dodecane (0.2 mL), zinc dust (3 g, 46 mmol), a carbonyl compound 1 (10 mmol), an aryl bromide 2 (15 mmol), and dimethyl itaconate 3 (7.9 g, 50 mmol) were added under stirring. Cobalt bromide (0.44 g, 2 mmol), trifluoroacetic acid (0.1 mL) and 1,2-dibromoethane (0.2 mL) were added successively to the mixture which was heated at 60°C until complete consumption of the aryl bromide (45 min. to 3 h, monitored by gas chromatography). The reaction mixture was then filtered through celite. Celite was washed several times with diethyl ether and the combined organic fractions were concentrated in vacuo. The crude reaction product was purified via flash column chromatography over silica gel using a pentane/diethyl ether (1:0 to 0:1) as an eluant to afford the five-membered ring lactone 4 as a mixture of diastereoisomers (50:50 to 70:30 typically).
AC C
EP
TE D
Diastereoisomers of compound 4x were separated using consecutive chromatographies using flash cartridges of opposite polarities. Diastereoisomer 4xB was obtained using a polar Merck EVFD24 Si60 15-40µm phase and a petroleum ether/ethyle acetate 100:0 to 85:15 gradient whereas 4xA was obtained from the remaining mixture of 4xA and 4xB using an apolar C18 Grace reversed-phase and a MeOH/H2O 50:50 to 80:20 gradient.
ACCEPTED MANUSCRIPT 4.4. Compounds characterization Methyl 3-benzyl-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4a Prepared following general procedure, using benzaldehyde (1.0 mL, 10 mmol, 1 eq.) and bromobenzene (1.6 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4aA and 4aB were obtained in a 76 : 24 ratio as a colorless H oil; yield: 1.99 g (64 %); Rf: 0.10 (pentane/diethyl ether mixture (7:3)); 1H NMR (CDCl3): δ = 2.19 (1HA, d, CO2Me J 13.7), 2.70 (1HB, d, J 17.5), 2.72 (1HA, d, J 17.6), 2.87 (1HA, d, J 13.7), 3.01 (1HB, d, J 13.8), 3.09 (1HB, d, J 17.5), 3.13 (1HA, d, J 17.6), 3.33 (3HA, s), 3.63 (1HB, d, J 13.8), 3.77 (3HB, s), 5.44 (1HA, s), 5.75 (1HB, s), 6.95 (2HA, dd, J 2.3, 7.8), 7.15 (2HB, dd, J 1.8, 8.1), 7.22 (2HA, d, J 7.8), 7.30 (2HB, d, J 8.1), 7.28-7.45 (12HA+B, m); 13C NMR (CDCl3): δ = 35.6 (1CA), 35.8 (1CB), 39.0 (1CA), 40.8 (1CB), 52.1 (1CB), 52.9 (1CA), 56.3 (1CA), 58.1 (1CB), 85.7 (1CA), 87.0 (1CB), 125.9 (1CA), 126.5 (1CB), 127.3-129.9 (20CA+B), 134.3 (1CB), 134.9 (1CA), 135.5 (1CA), 135.7 (1CB), 170.9 (1CB), 173.0 (1CA), 174.5 (1CA), 174.6 (1CB); IR: ν = 701, 747, 1011, 1165, 1200, 1733, 1785, 2953 cm-1; MS (EI): m/z = 233 (5), 219 (23), 218 (8), 205 (12), 204 (100), 203 (14), 191 (8), 187 (5), 186 (5), 176 (42), 172 (27), 145 (9), 144 (12), 134 (9), 117 (20), 116 (27), 115 (25), 91 (12); Anal. calcd. for C19H18O4 (310.12): C 73.53, H 5.85; found: C 73.21, H 5.71. O
RI PT
O
Methyl 3-(4-methoxycarbonylbenzyl)-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4b
Prepared following general procedure, using benzaldehyde (1.0 mL, 10 mmol, 1 eq.) and methyl-4bromobenzoate (3.22 g, 15 mmol, 1.5 eq.). Both diastereoisomers 4bA and 4bB were obtained in a 75 : H 25 ratio as a colorless oil; yield: 3.65 g, (99 %); Rf: 0.14 (pentane/diethyl ether mixture (7:3)); 1H NMR CO2 Me (CDCl3): δ = 2.12 (1HB, d, J 13.7), 2.57 (1HB, d, J 17.5), 2.58 (1HA, d, J 17.6), 2.79 (1HB, d, J 13.7), 2.90 (1HB, d, J 17.5), 2.92 (1HA, d, J 13.5), 3.01 (1HA, d, J 17.6), 3.20 (3HA, s), 3.56 (1HA, d, J 13.5), 3.65 (3HB, s), 3.76 (3HB, s), 3.77 (3HA, s), 5.32 (1HA, s), 5.64 (1HB, s), 6.92 (2HB, d, J 8.3), 7.11 (2HA, d, J 8.0), 7.14-7.33 (10HA+B, m), 7.57 (2HB, d, J 8.3), 7.84 (2HA, d, J 8.3); 13C NMR (CDCl3): δ = 35.6 (1CB), 36.0 (1CA), 38.9 (1CB), 40.7 (1CA), 52.1 (2CA), 53.0 (2CB), 56.0 (1CB), 58.1 (1CA), 85.6 (1CB), 87.2 (1CA), 125.9 (2CA+B), 125.7 (2CA), 126.4 (2CB), 128.4 (2CA), 128.6 (2CB), 129.0 (2CA+B), 129.3 (2CB), 129.5 (2CB), 129.7 (2CA), 129.8 (2CA), 134.1 (1CB), 134.6 (1CA), 140.1 (1CA), 140.9 (1CB), 166.7 (2CA+B), 170.6 (1CB), 172.7 (1CA), 174.2 (2CA+B); IR: ν = 702, 755, 1015, 1108, 1180, 1220, 1362, 1715, 1790, 2954 cm-1; MS (EI): m/z = 368 (4), 337 (15), 336 (5), 263 (22), 262 (100), 261 (5), 247 (7), 235 (15), 234 (91), 231 (7), 230 (21), 219 (28), 204 (5), 203 (22), 202 (18), 192 (33), 191 (6), 175 (28), 174 (26), 171 (9), 159 (7), 158 (6), 150 (22), 143 (22), 131 (6), 116 (6), 115 (17), 91 (13); Anal. calcd. for C21H20O6 (368.13): C 68.47, H 5.47; found: C 68.48, H 5.41. CO 2Me
SC
O
M AN U
O
Methyl 3-(4-(trifluoromethylbenzyl)-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4c CF3
AC C
EP
TE D
Prepared following general procedure, using benzaldehyde (1.0 mL, 10 mmol, 1 eq.) and 4bromobenzotrifluoride (2.10 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4cA and 4cB were obtained in a H 88 : 12 ratio as a colorless oil; yield: 2.03 g (54 %); Rf: 0.10 (pentane/diethyl ether mixture (7:3)) ; 1H CO2Me NMR (CDCl3): δ = 2.26 (1HB, d, J 13.8), 2.68 (1HB, d, J 17.6), 2.68 (1HA, d, J 17.2), 2.92 (1HB, d, J 13.8), 3.00 (1HA, d, J 13.6), 3.00 (1HA, d, J 17.2), 3.15 (1HB, d, J 17.6), 3.31 (3HA, s), 3.67 (1HA, d, J 13.6), 3.78 (3HB, s), 5.43 (1HA, s), 5.75 (1HB, s), 7.10 (2HB, d, J 8.1), 7.27 (2HA, d, J 8.2), 7.28-7.37 (10HA+B, m), 7.46 (2HB, d, J 8.1), 7.53 (2HA, d, J 8.2); 13C NMR (CDCl3): δ = 35.7 (1CB), 36.2 (1CA), 38.5 (1CB), 40.3 (1CA), 52.2 (1CA), 52.3 (1CB), 56.0 (1CB), 58.1 (1CA), 85.6 (1CB), 87.3 (1CA), 123.9 (2CA, q, J 272.0), 125.5 (4CA+B, q, J 3.7), 125.8 (2CA, q, J 273.4), 126.4 (2CB), 126.5 (2CA), 128.7 (2CB), 128.8 (2CA), 129.2 (1CB), 129.3 (1CA), 129.6 (1CA, q, J 33.0), 129.7 (1CB, q, J 33.1),130.0 (2CB), 130.2 (2CA), 134.0 (1CB), 134.6, (1CA), 139.9 (1CB), 140.0 (1CA), 170.6 (1CA), 172.6 (1CB), 174.0 (1CB), 174.2 (1CA); 19F NMR (CDCl3): δ = -62.6 (6FA+B); IR: ν = 701, 1016, 1114, 1164, 1324, 1712, 1791, 2361, 2955 cm-1; MS (EI): m/z = 273 (14), 272 (100), 245 (9), 244 (64), 240 (18), 219 (9), 213 (10), 212 (10), 202 (304), 185 (18), 184 (20), 175 (6), 165 (9), 115 (10); Anal. calcd. for C20H17F3O4 (378.11): C 63.49, H 4.53; found: C 63.25, H 4.66. O
O
Methyl 3-(3-(trifluoromethylbenzyl)-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4d Prepared following general procedure, using benzaldehyde (1.0 mL, 10 mmol, 1 eq.) and 3bromobenzotrifluoride (2.1 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4dA and 4dB were obtained in H a 35 : 65 ratio as a colorless solid, mp: 107°C; yield: 1.80 g (48 %); Rf: 0.25 (pentane/diethyl ether CO2Me mixture (7:3)); 1H NMR (CDCl3): δ = 2.29 (1HB, d, J 13.8), 2.72 (1HB, d, J 17.6), 2.74 (1HA, d, J 17.3), 2.93 (1HB, d, J 13.8), 3.03 (1HA, d, J 17.3), 3.04 (1HA, d, J 13.7), 3.15 (1HB, d, J 17.6), 3.33 (3HA, s), 3.69 (1HA, d, J 13.7), 3.79 (3HB, s), 5.47 (1HA, s), 5.80 (1HB, s), 7.19 (1HB, d, J 8.0), 7.24 (1HB, s), 7.30-7.39 (16HA+B, m); 13C NMR (CDCl3): δ = 35.5 (1CB), 36.4 (1CA), 40.2 (1CB), 41.1 (1CA), 52.1 (1CA), 52.9 (1CB), 56.1 (1CB), 58.3 (1CA), 85.5 (1CB), 87.3 (1CA), 123.8 (1CB, q, J 272.0), 123.9 (1CA, q, J 272.1), 124.1 (1CB, q, J 4.0), 124.3 (1CA, q, J 3.9), 125.6 (2CA), 126.2 (1CB, q, J 4.0), 126.5 (2CB), 126.6 (1CA, q, J 4.1), 128.6 (2CA), 128.8 (2CB), 129.1 (1CB), 129.2 (1CA), 129.3 (1CB), 129.4 (1CA), 130.8 (1CB, q, J 32.0), 130.9 (1CA, q, J 32.0), 133.1 (1CA), 133.3 (1CB), 134.2 (1CB), 134.6 (1CA), 136.8 (1CB), 136.9 (1CA), 170.6 (1CA), 172.7 (1CB), 174.2 (1CA + 1CB); 19F NMR (CDCl3): δ = -62.9 (6FA+B); IR: ν = 701, 757, 1014, 1120, 1162, 1330, 1452, 1732, 1789, 2953 cm-1; MS (EI): m/z = 234 (19), 232 (6), 204 (12), 203 (73), 201 (12), 200 (43), 192 (7), 175 (22), 174 (15), 173 (8), 172 (6), 145 (7), 132 (7), 131 (6), 129 (14), 128 (100), 117 (5), 116 (9), 115 (12), 105 (31), 100 (17), 99 (16), 91 (7), 85 (17), 77 (22), 51 (6); Anal. calcd. for C20H17F3O4 (378.11): C 63.49, H 4.53; found: C 63.33, H 4.31. O
O
CF3
ACCEPTED MANUSCRIPT
Methyl 3-(2-(trifluoromethylbenzyl)-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4e Prepared following general procedure, at room temperature, using benzaldehyde (1.0 mL, 10 mmol, 1 eq.) and 2-bromobenzotrifluoride (2.0 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4eA and 4eB were obtained H in a 35 : 65 ratio as a colorless oil; yield: 2.09 g (55 %); Rf: 0.32 (pentane/diethyl ether mixture (7:3)); 1H CF 3 CO2Me NMR (CDCl3): δ = 2.48 (1HA, d, J 17.6), 2.59 (1HB, d, J 17.8), 2.73 (1HB, d, J 15.8), 3.02 (1HB, d, J 15.8), 3.16 (1HA, d, J 17.5), 3.24 (1HB, d, J 17.8), 3.34 (3HA, s), 3.36 (1HA, d, J 15.7), 3.86 (3HB, s), 3.92 (1HA, d, J 15.7), 5.49 (1HA, s), 5.74 (1HB, s), 7.02 (1HB, d, J 7.8), 7.14 (1HA, d, J 7.8), 7.15-7.43 (14HA+B, m), 7.62 (1HB, d, J 7.8), 7.69 (1HA, d, J 7.8); 13C NMR (CDCl3): δ = 33.6 (1CB), 35.7 (1CB), 35.9 (1CA), 36.2 (1CA), 52.5 (1CA), 53.3 (1CB), 55.2 (1CB), 57.3 (1CA), 86.0 (1CB), 87.7 (1CA), 124.1 (2CA+B, q, J 272.0), 125.8 (1CB), 126.5 (1CA), 126.5 (2CA+B, q, J 10.0), 127.2 (1CB), 127.3 (1CA), 128.5 (2CA), 128.6 (2CB), 129.2 (2CB), 129.3 (2CA), 129.4 (1CA + 1CB, q, J 29.0), 129.5 (1CB), 129.6 (1CA), 132.0 (1CB), 132.3 (1CA), 134.0 (1CB), 134.6 (1CA), 135.0 (1CB), 135.1 (1CA), 171.6 (1CA), 173.7 (1CB), 174.1 (1CB), 174.2 (1CA); 19F NMR (CDCl3): δ = -57.2 (6FA+B); IR: ν = 771, 1014, 1116, 1161, 1217, 1312, 1440, 1632, 1712, 2956 cm-1; MS (EI): m/z = 273 (14), 272 (100), 252 (8), 244 (31), 240 (26), 225 (9), 224 (5), 219 (8), 213 (10), 212 (6), 209 (11), 207 (11), 204 (14), 202 (25), 193 (18), 185 (8), 173 (20), 165 (12), 164 (6), 159 (6), 115 (5); Anal. calcd. for C20H17F3O4 (378.11): C 63.49, H 4.53; found: C 63.29, H 4.61. O
RI PT
O
Methyl 3-(4-methoxybenzyl)-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4f
Prepared following general procedure, using benzaldehyde (1 mL, 10 mmol, 1 eq.) and 4-bromoanisole (1.8 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4fA and 4fB were obtained as a colorless oil; yield: H 3.24 g (95%); Rf: 0.14 (pentane/diethyl ether mixture (7:3)); Diastereoisomers could be separated from CO2 Me this mixture. Diastereoisomer 4fA: 1H NMR (CDCl3): δ = 2.70 (1HA, d, J 17.6), 2.92 (1HA, d, J 13.9), 3.07 (1HA, d, J 17.6), 3.33 (3HA, s), 3.57 (1HA, d, J 13.9), 3.79 (3HA, s), 5.43 (1HA, s), 6.84 (2HA, d, J 8.7), 7.07 (2HA, d, J 8.7), 7.28 (2HA, d, J 7.3), 7.38-7.40 (3HA, m); 13C NMR (CDCl3): δ = 35.7 (1CA), 40.1 (1CA), 52.1 (1CA), 55.3 (1CA), 58.3 (1CA), 87.1 (1CA), 114.0 (2CA), 125.2 (2CA), 127.4, (1CA), 128.5 (2CA), 129.1 (1CA), 131.0 (2CA), 134.9 (1CA), 158.9 (1CA), 170.9 (1CA), 174.6 (1CA); Diastereoisomer 4fB: 1H NMR (CDCl3): δ = 2.14 (1HB, d, J 13.9), 2.72 (1HB, d, J 17.7), 2.81 (1HB, d, J 13.9), 3.13 (1HB, d, J 17.7), 3.75 (3HB, s), 3.78 (3HB, s), 5.74 (1HB, s), 6.76 (2HB, d, J 8.7), 6.88 (2HB, d, J 8.7), 7.36 (2HB, d, J 7.1), 7.40-7.43 (3HB, m); 13C NMR (CDCl3): δ = 31.0 (1CB), 35.6 (1CB), 52.9 (1CB), 56.3 (1CB), 58.3 (1CB), 87.0 (1CB), 114.2 (2CB), 125.9 (2CB), 126.5 (1CB), 128.5 (2CB), 128.8 (1CB), 130.5 (2CB), 134.4 (1CB), 158.7 (1CB), 171.5 (1CB), 173.0 (1CB); IR: ν = 701, 728, 834, 1176, 1297, 1512, 1731, 1786, 2953 cm-1; MS (EI): m/z = 341 (9), 340 (43), 263 (5), 234 (16), 233 (6), 206 (28), 202 (6), 175 (8), 174 (8), 147 (14), 146 (21), 145 (7), 131 (5), 122 (12), 121 (100), 91 (7), 77 (7); Anal. calcd. for C20H20O5 (340.13): C 70.57, H 5.92; found: C 70.27 H 5.71. O
OMe
M AN U
SC
O
Methyl 3-(3-methoxybenzyl)-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4g OMe
AC C
EP
H
TE D
Prepared following general procedure, using benzaldehyde (1.0 mL, 10 mmol, 1 eq.) and 3bromoanisole (1.90 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4gA and 4gB were obtained in a 86 : 14 ratio as a colorless solid, mp: 52°C; yield: 1.51 g (44 %); Rf: 0.28 (pentane/diethyl ether mixture CO2Me (7:3)); 1H NMR (CDCl3): δ = 2.17 (1HA, d, J 13.7), 2.72 (1HB, d, J 17.6), 2.73 (1HA, d, J 17.7), 2.86 (1HA, d, J 13.7), 2.95 (1HB, d, J 13.7), 3.07 (1HB, d, J 17.6), 3.15 (1HA, d, J 17.7), 3.35 (3HB, s), 3.63 (1HB, d, J 13.7), 3.74 (3HA, s), 3.78 (3HB, s), 3.80 (3HA, s), 5.44 (1HB, s), 5.74 (1HA, s), 6.50 (1HA, d, J 2.0), 6.52 (1HA, d, J 7.9), 6.70 (1HB, d, J 2.0), 6.71 (1HB, d, J 7.9), 6.75 (1HA, dd, J 7.9, 2.0), 6.81 (1HB, dd, J 7.9, 2.0), 7.15 (1HA, t, J 7.9), 7.23 (1HB, t, J 7.9), 7.28-7.49 (10HA+B, m); 13C NMR (CDCl3): δ = 35.6 (1CA), 35.8 (1CB), 39.0 (1CA), 40.8 (1CB), 52.1 (1CB), 52.9 (1CA), 55.1 (2CA+B), 56.2 (1CA), 58.1 (1CB), 85.7 (1CA), 87.0 (1CB), 112.5 (1CA), 112.6 (1CB), 115.3 (1CA), 115.9 (1CB), 121.8 (1CA), 122.2 (1CB), 125.9 (2CB), 126.5 (2CA), 128.5 (2CB), 128.6 (2CA), 129.1 (1CA + 1CB), 129.2 (1CB), 129.6 (2CA), 129.8 (1CB), 134.3 (1CA), 134.9 (1CB), 137.2 (2CA+B), 173.0 (2CA+B), 174.5 (2CA+B); IR: ν = 699, 756, 1014, 1164, 1262, 1490, 1732, 1784, 2361, 2953 cm-1; MS (EI): m/z = 341 (10), 340 (48), 235 (6), 234 (30), 219 (14), 206 (16), 203 (6), 202 (15), 176 (8), 175 (53), 174 (38), 147 (22), 146 (39), 145 (7), 131 (8), 123 (9), 122 (100), 121 (7), 115 (10), 103 (7), 91 (16), 77 (8); Anal. calcd. for C20H20O5 (340.13): C 70.57, H 5.92; found: C 70.87, H 5.91. O
O
Methyl 3-(2-methoxybenzyl)-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4h Prepared following general procedure, at room temperature, using benzaldehyde (1.0 mL, 10 mmol, 1 eq.) and 2-bromoanisole (0.94 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4hA and 4hB were obtained in a H 43 : 57 ratio as a colorless solid, mp: 73°C; yield: 2.43 g (71 %); Rf: 0.25 (pentane/diethyl ether mixture OMe CO2Me (7:3)); 1H NMR (CDCl3): δ = 2.54 (1HB, d, J 13.7), 2.72 (1HA, d, J 17.6), 2.73 (1HB, d, J 13.7), 2.77 (1HB, d, J 17.6), 3.01 (1HA, d, J 17.6), 3.08 (1HB, d, J 17.6), 3.34 (1HA, d, J 13.3), 3.34 (3HA, s), 3.38 (1HA, d, J 13.3), 3.76 (3HB, s), 3.77 (3HB, s), 3.85 (3HA, s), 5.50 (1HA, s), 5.75 (1HB, s), 6.79-6.83 (2HA+B, m), 6.92-6.94 (3HA+B, m), 7.107.12 (1HA, m), 7.17-7.18 (1HA, m), 7.19-7.21 (1HB, m), 7.22-7.27 (10HA+B, m); 13C NMR (CDCl3): δ = 31.8 (1CB), 33.6 (1CA), 35.3 (1CA), 36.0 (1CB), 52.0 (1CA), 52.7 (1CB), 55.0 (1CB), 55.2 (1CA), 56.2 (1CB), 58.0 (1CA), 85.6 (1CB), 86.5 (1CA), 110.3 (1CA), 110.7 (1CB), 120.5 (1CB), 120.8 (1CA), 124.1 (1CB), 124.2 (1CA), 126.7 (1CA), 128.2 (1CB), 128.3-128.8 (10CA+B), 131.2 (1CB), 131.6 (1CA), 134.5 (1CA), 135.3 (1CB), 157.5 (1CB), 157.6 (1CA), 171.5 (1CA), 173.2 (1CB), 175.0 (1CB), 175.3 (1CA); IR: ν = 753, 893, 1014, 1171, 1245, 1494, 1732, 1788, 2361, 2901, 2988 cm-1; MS (EI): m/z = 341 (6), 340 (22), 290 (7), 281 (7), 280 (7), 263 (8), 262 (6), 235 (19), 234 (100), 233 (16), 219 (34), 206 (7), 203 (16), 202 (12), 191 (13), 187 (10), 175 (30), 174 (77), 159 (8), 147 (6), 146 (7), 145 (9), 132 (6), 131 (14), 126 (54), 123 (8), 122 (73), 121 (37), 115 (7), 105 (5), 93 (10), 91 (32), 77 (8), 65 (8); Anal. calcd. for C20H20O5 (340.13): C 70.57, H 5.92; found: C 70.31, H 5.99. O
O
ACCEPTED MANUSCRIPT
Methyl 3-(benzo[d][[1,3]]dioxol-5-ylmethyl)-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4i Prepared following general procedure, using benzaldehyde (0.5 mL, 5 mmol, 1 eq.) and 4-bromo-1,3dioxole (0.90 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4iA and 4iB were obtained in a 37 : 63 ratio H as a yellow oil ; yield: 0.59 g (33 %); Rf: 0.14 (pentane/diethyl ether mixture (7:3)); 1H NMR (CDCl3): δ CO2 Me = 2.07 (1HB, d, J 13.9), 2.65-2.72 (3HB, m), 2.83 (1HA, d, J 13.8), 2.99 (1HA, d, J 17.5), 3.10 (1HB, d, J 17.6), 3.28 (3HA, s), 3.49 (1HA, d, J 13.8), 3.74 (3HB, s), 5.36 (1HA, s), 5.68 (1HB, s), 5.82 (2HA, s), 5.86 (2HB, s), 6.35-6.40 (3HA, m), 6.58-6.67 (3HB, m), 7.22-7.48 (10HA+B, m); 13C NMR (CDCl3): δ = 35.3 (1CB), 35.5 (1CA), 38.7 (1CB), 40.3 (1CA), 52.1 (1CA), 52.9 (1CB), 56.3 (1CB), 58.4 (1CA), 85.5 (1CB), 87.0 (1CA), 101.1 (2CA+B), 107.8 (1CB), 108.0 (1CA), 109.6 (1CB),, 110.0 (1CA), 122.8 (1CB), 123.2 (1CA), 125.5 (2CA), 125.8 (2CB), 128.2 (2CA), 128.5 (2CB), 129.1 (1CB), 129.2 (1CA), 134.8 (1CB), 135.0 (1CA), 146.7 (1CB), 146.9 (1CA), 147.8 (2CB), 147.9 (2CA), 170.9 (1CA), 172.9 (1CB), 174.5 (1CB), 174.6 (1CA); IR: ν = 701, 753, 925, 1012, 1034, 1167, 1245, 1443, 1489, 1730, 1785, 2953 cm-1; MS (EI): m/z = 355 (23), 354 (100), 277 (6), 248 (15), 221 (6), 220 (33), 216 (9), 189 (14), 188 (6), 161 (12), 160 (36), 159 (6), 136 (28), 135 (74), 131 (6), 103 (7), 102 (8), 79 (5), 77 (16), 51 (5); HRMS: m/z (ESI) calcd. for C20H18O6Na (M+22.9898): 377.09956; found: 377.09980. O
O
O
RI PT
O
Methyl 5-oxo-2-phenyl-3-(3,4,5-trimethoxybenzyl)tetrahydrofuran-3-carboxylate 4j
Prepared following general procedure, using benzaldehyde (0.5 mL, 5 mmol, 1 eq.) and 3,4,5trimethoxybromobenzene (1.82 g, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4jA and 4jB were obtained O OMe H in a 64 : 36 ratio as a yellow oil; global yield: 1.12 g (56%); Rf: 0.06 (pentane/diethyl ether mixture (7:3)); 1H NMR (CDCl3): δ = 2.22 (1HB, d, J 13.8), 2.84-2.97 (4HA+B, m) 3.17 (1HA, d, J 17.6), 3.29 CO2Me (1HB, d, J 17.7), 3.41 (3HB, s), 3.66 (1HA, d, J 13.8), 3.84 (9HB, s), 3.87 (9HA, s), 3.89 (3HA, s), 5.54 (1HA, s), 5.83 (1HB, s), 6.24 (2HB, s), 6.44 (2HA, s), 7.33-7.50 (10HA+B, m); 13C NMR (CDCl3): δ = 36.1 (1C, C4B), 36.5 (1C, C6A), 39.1 (1C, C6B), 41.0 (1C, C4A), 52.2 (1C, C14A), 53.0 (1C, C14B), 56.2 (3CA), 58.5 (2CA+B), 61.0 (3CB), 86.0 (1CB), 87.8 (1CA), 106.5 (2CB), 106.9 (2CA), 125.8 (1CA), 126.1 (1CB), 128.6 (4CA+B), 129.1 (2CB), 129.3 (2CA), 131.3 (2CA+B), 133.9 (1CB), 134.5 (1CA), 136.9 (1CB), 137.1 (1CA), 153.1 (2CB), 153.2 (2CA), 170.8 (1CA), 172.9 (1CB), 175.6 (1CB), 176.1 (1CA); IR: ν = 702, 756, 1011, 1124, 1222, 1362, 1423, 1456, 1590, 1704, 1790, 2942 cm-1; MS (EI): m/z = 401 (8), 400 (29), 235 (6), 207 (11), 191 (7), 183 (12), 182 (100), 181 (40), 167 (16), 152 (6), 151 (28), 148 (10), 139 (5), 77 (7); HRMS: m/z (ESI) calcd. for C22H24O7Na (M+22.9898): 423.14142; found: 423.14153. OMe
M AN U
SC
MeO O
Methyl 2-(4-fluorophenyl)-3-(4-methoxybenzyl)-5-oxotetrahydrofuran-3-carboxylate 4k Prepared following general procedure, using 4-fluorobenzaldehyde (1.24 g, 10 mmol, 1 eq.) and 4bromoanisole (1.8 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4kA and 4kB were obtained in a 50 : 50 H ratio as a colorless oil; yield: 3.51 g (98 %); Rf: 0.14 (pentane/diethyl ether mixture (7:3)); 1H NMR (CDCl3): δ = 2.16 (1HB, d, J 15.0), 2.70 (1HB, d, J 17.6), 2.71 (1HA, d, J 17.8), 2.78 (1HB, d, J 15.0), CO2 Me F 2.90 (1HA, d, J 13.9), 3.02 (1HB, d, J 17.6), 3.13 (1HA, d, J 17.8), 3.35 (3HA, s), 3.53 (1HA, d, J 13.9), 3.73 (3HB, s), 3.75 (6HA+B, s), 5.40 (1HA, s), 5.69 (1HB, s), 6.76 (2HB, d, J 8.7), 6.83 (2HA, d, J 8.5), 6.87 (2HB, d, J 8.6), 7.07 (2HA, d, J 8.7), 7.06 (2HA, t, J 8.7), 7.13 (2HB, t, J 8.7), 7.27 (4HA+B, m); 13C NMR (CDCl3): δ = 35.6 (1CB), 35.8 (1CA), 38.0 (1CB), 39.9 (1CA), 52.1 (1CA), 52.8 (1CB), 55.2 (2CA+B), 56.3 (1CA), 58.2 (1CB), 84.3 (1CA), 86.3 (1CB), 114.0 (4CA+B), 115.5 (2CA, d, J 18.2), 115.7 (2CB, d, J 21.7), 127.3 (2CA+B), 127.7 (2CA, d, J 8.4), 128.4 (2CB, d, J 8.3), 130.1 (2CA+B, d, J 3.1), 130.9 (4CA+B), 158.9 (2CA+B), 163.0 (1CA, d, J 248.4), 163.1 (1CB, d, J 248.2), 170.9 (1CA), 172.8 (1CB), 174.2 (1CA), 174.4 (1CB); 19 F NMR (CDCl3): δ = -112.1 (2FA+B); IR: ν = 822, 842, 1010, 1020, 1234, 1359, 1609, 1671, 3002 cm-1; MS (EI): m/z = 359 (10), 358 (45), 234 (24), 207 (8), 206 (42), 202 (12), 175 (10), 174 (8), 147 (19), 146 (29), 145 (6), 131 (7), 123 (7), 122 (15), 121 (100), 91 (8), 77 (6); Anal. calcd. for C20H19FO5 (358.12): C 67.03, H 5.34; found: C 67.43, H 5.55. OMe
O
AC C
EP
TE D
O
Methyl 3-(4-methoxybenzyl)-5-oxo-2-(4-(trifluoromethyl)phenyl)tetrahydrofuran-3-carboxylate 4l Prepared following general procedure, using 4-trifluoromethylbenzaldehyde (0.7 mL, 5 mmol, 1 eq.) and 4-bromoanisole (0.9 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4lA and 4lB were obtained in a H 50 : 50 ratio as a colorless oil; yield: 1.36 g (67%); Rf: 0.17 (pentane/diethyl ether mixture (7:3)); 1H CO2 Me NMR (CDCl3): δ = 1.94 (1HA, d, J 14.1), 2.50 (3HA+B, m), 2.71 (1HB, d, J 14.6), 2.78 (1HA, d, J 17.5), F3C 2.93 (1HB, d, J 17.8), 3.09 (3HA, s), 3.32 (1HB, d, J 14.6), 3.51 (3HB, s), 3.54 (3HA, s), 3.56 (3HB, s), 5.23 (1HA, s), 5.53 (1HB, s), 6.53 (2HA, d, J 6.8), 6.61 (4HA+B, m), 6.83 (2HB, d, J 8.6), 7.19 (2HA, d, J 8.2), 7.30 (2HA, d, J 8.2), 7.41 (2HB, d, J 8.2), 7.43 (2HB, d, J 8.2); 13C NMR (CDCl3): δ = 35.7 (1CB), 36.0 (1CA), 37.9 (1CA), 39.8 (1CB), 52.1 (1CA), 52.9 (1CB), 55.1 (1CA), 55.2 (1CB), 56.0 (1CB), 58.4 (1CA), 84.5 (1CB), 86.0 (1CA), 114.0 (2CA), 114.2 (2CB), 125.5 (4CA+B, q, J 6.4), 126.3 (2CA), 126.4 (2CA+B), 126.9 (1CA, q, J 239.9), 127.0 (1CB, q, J 240.0), 127.1 (2CB), 130.6 (2CA), 130.9 (2CB), 131.6 (2CA+B, q, J 27.4), 138.3 (1CA), 139.1 (1CB), 158.8 (1CA), 159.0 (1CB), 170.7 (1CA), 172.6 (1CB), 174.0 (1CA), 174.2 (1CB); 19F NMR (CDCl3): δ = -62.6 (6FA+B); IR: ν = 839, 1012, 1068, 1115, 1166, 1325, 1512, 1698, 1732, 2956 cm-1; MS (EI): m/z = 408 (18), 146 (6), 122 (10), 121 (100), 91 (8), 77 (7); HRMS: m/z (ESI) calcd. for C21H19F3O5Na (M+22.9898): 431.10768; found: 431.10804. O
O
OMe
ACCEPTED MANUSCRIPT
Methyl 3-(4-methoxybenzyl)-5-oxo-2-(3-trifluoromethyl)phenyl)tetrahydrofuran-3-carboxylate 4m Prepared following general procedure, using 3-trifluoromethylbenzaldehyde (0.70 mL, 5 mmol, 1 eq.) and 4-bromoanisole (0.9 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4mA and 4mB were obtained O H in a 64 : 36 ratio as a colorless oil; yield: 1.43 g (78%); Rf: 0.20 (pentane/diethyl ether mixture F3C CO2Me (7:3)); 1H NMR (CDCl3): δ = 2.17 (1HB, d, J 13.8), 2.70 (3HA+B, m), 2.90 (1HA, d, J 13.8), 2.97 (1HA, d, J 17.5), 3.15 (1HB, d, J 17.8), 3.32 (3HA, s), 3.51 (1HA, d, J 13.8), 3.71 (3HB, s), 3.74 (3HA, s), 3.76 (3HB, s), 5.43 (1HA, s), 5.71 (1HB, s), 6.73 (2HB, d, J 8.6), 6.82 (4HA+B, m), 7.03 (2HA, d, J 8.6), 7.44-7.56 (8HA+B, m); 13C NMR (CDCl3): δ = 35.8 (1CB), 35.9 (1CA), 37.7 (1CB), 39.7 (1CA), 52.1 (1CA), 52.9 (1CB), 55.1 (1CA), 55.2 (1CB), 56.0 (1CB), 58.4 (1CA), 84.4 (1CB), 85.9 (1CA), 114.1 (2CB), 114.2 (2CA), 122.9 (1CA, q, J 3.8), 123.7 (1CB, q, J 3.8), 125.8 (1CA, q, J 3.7), 126.9 (1CB), 127.1 (1CA), 128.4 (1CB, q, J 290.8), 128.6 (1CA, q, J 290.8), 129.2 (1CB, q, J 3.9), 130.0 (2CA+B), 130.5 (2CA+B), 130.6 (2CB), 130.9 (2CA), 131.1 (1CB, q, J 23.7), 131.4 (1CA, q, J 23.7), 135.4 (1CB), 136.2 (1CA), 158.9 (1CB), 159.0 (1CA), 170.7 (1CA), 172.4 (1CB), 173.9 (1CB), 174.1 (1CA); 19F NMR (CDCl3): δ = -62.6 (6FA+B); IR: ν = 702, 804, 1022, 1074, 1123, 1166, 1330, 1513, 1612, 1732, 2955 cm-1; MS (EI): m/z = 407 (18), 146 (7), 145 (6), 122 (9), 121 (100), 91 (9), 77 (8); HRMS: m/z (ESI) calcd. for C21H19F3O5Na (M+22.9898): 431.10768; found: 431.10807.
RI PT
OMe
O
Methyl 3-(4-methoxybenzyl)-5-oxo-2-(2-trifluoromethyl)phenyl)tetrahydrofuran-3-carboxylate 4n
Prepared following general procedure, using 2-trifluoromethylbenzaldehyde (1.92 mL, 10 mmol, 1 eq.) and 4-bromoanisole (1.8 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4nA and 4nB were obtained in a H 75 : 25 ratio as a colorless oil; yield: 2.30 g (56 %); Rf: 0.17 (pentane/diethyl ether mixture (7:3)); 1H CO2 Me NMR (CDCl3): δ = 2.15 (1HB, d, J 13.7), 2.86 (1HB, d, J 18.3), 2.88 (1HA, d, J 17.8), 2.97 (1HA, d, J CF3 13.8), 3.03 (1HB, d, J 13.7), 3.12 (1HA, d, J 17.8), 3.29 (3HA, s), 3.37 (1HB, d, J 18.3), 3.59 (1HA, d, J 13.8), 3.76 (3HB, s), 3.79 (3HB, s), 3.80 (3HA, s), 5.93 (1HA, s), 6.23 (1HB, s), 6.81 (2HA, d, J 8.5), 6.84 (2HB, d, J 8.5), 6.92 (2HB, d, J 8.5), 7.06 (2HA, d, J 8.5), 7.35-7.85 (8HA+B, m); 13C NMR (CDCl3): δ = 35.4 (1CB), 36.0 (1CA), 37.8 (1CB), 41.5 (1CA), 51.9 (1CA), 52.8 (1CB), 55.0 (1CB), 56.7 (1CA), 58.3 (2CA+B), 81.2 (1CB), 82.5 (1CA), 113.9 (2CB), 114.1 (2CA), 123.9 (1CB, q, J 274.2), 124.0 (1CA, q, J 274.2), 126.1 (1CA, q, J 5.5), 126.7 (1CB, q, J 5.4), 127.1 (1CB),, 127.5 (1CA), 127.8 (1CA), 128.0 (1CB), 128.8 (1CA, q, J 28.6), 128.9 (1CB, q, J 28.7), 129.3 (1CA), 129.5 (1CB),, 130.3 (2CB), 130.6 (2CA), 132.0 (1CA), 132.3 (1CB), 133.7 (1CB, q, J 2.5), 134.7 (1CA, q, J 2.5),158.7 (1CA), 158.9 (1CB), 171.1 (1CA), 172.8 (1CB), 174.1 (1CA), 174.4 (1CB); 19F NMR (CDCl3): δ = -56.7 (6FA+B); IR: ν = 736, 769, 1009, 1161, 1206, 1513, 1735, 1791, 2955 cm-1; MS (EI): m/z = 408 (11), 207 (7), 146 (6), 122 (9), 121 (100); Anal. calcd. for C21H19F3O5 (408.12): C 61.76, H 4.69; found: C 61.85, H 4.76. OMe
O
M AN U
SC
O
Methyl 3-benzyl-5-oxo-2-(3,4,5-trimethoxyphenyl)tetrahydrofuran-3-carboxylate 4o Prepared following general procedure, using 3,4,5-trimethoxybenzaldehyde (0.98 g, 5 mmol, 1 eq.) and bromobenzene (0.8 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4oA and 4oB were obtained in a 50 : H MeO 50 ratio as a yellow oil; yield: 1.92 g (96%); Rf: 0.05 (pentane/diethyl ether mixture (7:3)); 1H NMR CO2Me (CDCl3): δ = 2.36 (1HB, d, J 13.6), 2.88-2.96 (3HA+B, m), 3.04-3.09 (2HA+B, m), 3.30 (1HA, d, J 18.2), MeO 3.43 (3HA, s), 3.59 (1HA, d, J 13.6), 3.66 (3HB, s), 3.90 (12HA+B, s), 3.92 (6HA+B, s), 5.63 (1HA, s), 5.85 OMe (1HB, s), 6.55 (2HA, s), 6.65 (2HB, s), 7.00-7.30 (10HA+B, m); 13C NMR (CDCl3): δ = 36.5 (1CA), 37.9 (1CB), 38.6 (1CB), 39.7 (1CA), 52.6 (1CA), 53.1 (1CB), 56.2 (1CB), 56.6 (6CA+B), 58.8 (1CA), 87.1 (1CB), 89.2 (1CA), 103.0, (2CA), 103.8 (2CB), 127.4 (1CA), 127.5 (1CB), 128.7 (2CA), 128.9 (2CB), 129.2 (2CA+B), 129.6 (2CB), 129.8 (2CA) 135.2 (1CB), 135.4 (1CA), 137.9 (1CB), 138.0 (1CA), 153.1 (4CA+B) 170.8 (1CA), 172.6 (1CB), 178.5 (1CB), 179.5 (1CA); IR: ν = 575, 700, 978, 1122, 1231, 1717, 2950 cm-1; MS (EI): m/z = 277 (33), 205 (9), 204 (57), 198 (12), 197 (45), 196 (63), 195 (7), 181 (22), 176 (33), 172 (17), 169 (11), 145 (7), 144 (9), 117 (15), 116 (17), 115 (15), 91 (7); HRMS: m/z (ESI) calcd. for C22H24O7Na (M+22.9898): 423.14142; found: 423.14168. O
EP
TE D
O
AC C
Methyl 3-(4-methoxybenzyl)-5-oxo-2-(3,4,5-trimethoxyphenyl)tetrahydrofuran-3-carboxylate 4p Prepared following general procedure, using 3,4,5-trimethoxybenzaldehyde (0.98 g, 5 mmol, 1 eq.) and 4-bromoanisole (0.9 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4pA and 4pB were obtained in H a 52 : 48 ratio as a pink oil; yield: 1.69 g (78%); Rf: 0.13 (pentane/diethyl ether mixture (7:3)); 1H MeO CO2Me NMR (CDCl3): δ = 2.17 (1HA, d, J 14.0), 2.64-2.72 (2HA+B, m), 2.81-2.87 (2HA+B, m), 2.99 (1HB, d, J MeO 17.5), 3.09 (1HA, d, J 17.7), 3.53 (1HB, d, J 14.0), 3.65-3.84 (30HA+B, m), 5.31 (1HA, s), 5.64 (1HB, s), OMe 6.45 (2HA, s), 6.53 (2HB, s), 6.73 (2HA, d, J 8.7), 6.80 (2HB, d, J 8.7), 6.86 (2HA, d, J 8.7), 7.04 (2HB, d, J 8.7); 13C NMR (CDCl3): δ = 35.8 (1CA), 36.2 (1CB), 37.8 (1CA), 40.0 (1CB), 52.2 (1CA), 52.9 (1CB), 55.2 (2CA+B), 56.3 (4CA+B), 58.4 (2CA+B), 60.8 (1CA), 60.9 (1CB), 85.6 (1CB), 87.2 (1CA), 103.0 (2CA), 103.5 (2CB), 113.6 (2CB), 114.0 (2CA), 127.4 (2CA+B), 129.2 (1CA), 129.4 (1CB), 130.6 (2CB), 130.9 (2CA), 138.3 (1CB), 138.4 (1CA), 153.3 (2CA), 153.4 (2CB), 158.8 (1CB), 158.9 (1CA), 171.0 (1CA), 173.0 (1CB), 174.7 (1CB), 174.8 (1CA); IR: ν = 586, 600, 1024, 1508, 1975, 2343, 2364, 2950 cm-1; MS (EI): m/z = 431 (29), 430 (100), 309 (13), 277 (45), 234 (43), 233 (31), 207 (19), 206 (61), 205 (25), 202 (15), 198 (11), 196 (20), 181 (15), 174 (12), 169 (12), 147 (28), 146 (33), 145 (18), 135 (11), 121 (15); HRMS: m/z (ESI) calcd. for C23H26O8Na (M+22.9898): 453.15199; found: 453.15217. O
O
OMe
ACCEPTED MANUSCRIPT Methyl 3-(3-methoxybenzyl)-5-oxo-2-(3,4,5-trimethoxyphenyl)tetrahydrofuran-3-carboxylate 4q Prepared following general procedure, using 3,4,5-trimethoxybenzaldehyde (0.98 g, 5 mmol, 1 eq.) and 3-bromoanisole (0.94 mL, 7.5 mmol, 1.5 eq.). Diastereoisomers 4qA and 4qB were H MeO obtained in a 45 : 55 ratio as a yellow oil; yield: 1.57 g (73 %); Rf: 0.04 (pentane/diethyl ether CO2Me mixture (7:3)); 1H NMR (CDCl3): δ = 2.20 (1HA, d, J 13.7), 2.71-2.93 (5HA+B, m), 3.12 (1HA, MeO d, J 17.9), 3.35 (3HA, s), 3 31 (3HB, s), 3.51 (1HB, d, J 13.5), 3.60-3.83 (24HA+B, m), 5.36 OMe (1HA, s), 5.64 (1HB, s), 6.44-6.52 (6HA+B, m), 6.63-6.74 (4HB, m), 7.07-7.16 (2HA, m); 13C NMR (CDCl3): δ = 36.0 (1CA), 36.8 (1CB), 37.6 (1CA), 40.3 (1CB), 52.3 (2CA+B), 52.9 (2CA+B), 55.2 (2CA), 56.2 (1CB), 56.4 (2CB), 58.3 (1CA), 61.0 (2CA+B), 85.8 (1CB), 87.6 (1CA), 103.0 (2CA), 103.7 (2CB), 112.5 (2CA+B), 115.4 (1CB), 115.7 (1CA), 121.8 (1CB), 122.1 (1CA), 129.6 (1CB), 129.8 (1CA), 130.1 (2CA+B), 137.0 (2CA+B), 138.2 (1CA), 138.4 (1CB), 153.2 (2CA), 153.3 (2CB), 159.7 (1CB), 159.8 (1CA), 171.0 (1CA), 172.9 (1CB), 175.5 (1CA), 175.9 (1CB); IR: ν = 700, 922, 1003, 1124, 1156, 1222, 1331, 1425, 1461, 1509, 1593, 1709, 1787, 2947 cm-1; MS (EI): m/z = 431 (23), 430 (100), 309 (33), 281 (19), 277 (59), 234 (37), 219 (15), 209 (17), 208 (15), 207 (66), 202 (14), 197 (20), 196 (45), 191 (16), 181 (22), 175 (51), 174 (23), 147 (18), 146 (33), 122 (35); HRMS: m/z (ESI) calcd. for C23H26O8Na (M+22.9898): 453.15199; found: 453.15208. O
O
RI PT
OMe
Methyl 3-(2-methoxybenzyl)-5-oxo-2-(3,4,5-trimethoxyphenyl)tetrahydrofuran-3-carboxylate 4r
Prepared following general procedure, at room temperature, using 3,4,5trimethoxybenzaldehyde (0.98 g, 5 mmol, 1 eq.) and 2-bromoanisole (0.94 mL, 7.5 mmol, H MeO 1.5 eq.). Diastereoisomers 4rA and 4rB were obtained in a 50 : 50 ratio as a yellow oil; yield: OMe CO2 Me 2,13 g (98 %); Rf: 0.01 (pentane/diethyl ether mixture (7:3)); 1H NMR (CDCl3): δ = 2.59 (1HA, MeO d, J 13.6), 2.70-2.77 (4HA+B, m), 2.97 (1HB, d, J 17.5), 3.07 (1HA, d, J 17.7), 3.35 (4HB, m), 3.74OMe 3.89 (27HA+B, m), 5.43 (1HA, s), 5.70 (1HB, s), 6.55 (2HA, s), 6.62 (2HB, s), 6.79-6.94 (5HA+B, m), 7.07 (1HB, m), 7.17-7.27 (2HA+B, m); 13C NMR (CDCl3): δ = 31.5 (1CA), 33.4 (1CB), 35.8 (1CB), 36.1 (1CA), 52.2 (1CB), 52.7 (1CA), 55.1 (1CA), 55.2 (1CB), 56.2 (4CA+B), 58.1 (2CA+B), 60.9 (2CA+B), 85.7 (1CB), 86.7 (1CA), 103.0 (2CA), 103.8 (2CB), 110.4 (1CA), 110.8 (1CB), 120.5 (1CA), 120.9 (1CB), 123.9 (1CA), 124.1 (1CB),128.6 (1CA), 128.9 (1CB), 129.9 (1CA), 130.6 (1CB), 131.2 (1CA), 131.6 (1CB), 138.2 (1CA), 138.4 (1CB), 153.2, (4CA+B), 157.5 (1CA), 157.6 (1CB), 171.5 (1CA), 173.2 (1CB), 175.5 (1CA), 175.9 (1CB); IR: ν = 729, 1125, 1242, 1509, 1732, 1787, 2943 cm-1; MS (EI): m/z = 431 (22), 430 (100), 309 (26), 308 (13), 281 (22), 277 (46), 234 (39), 209 (21), 208 (21), 207 (96), 206 (11), 196 (22), 191 (19), 181 (15), 175 (30), 174 (30), 131 (24), 126 (39), 121 (34), 91 (23); HRMS: m/z (ESI) calcd. for C23H26O8Na (M+22.9898): 453.15199; found: 453.15221.
SC
O
M AN U
O
TE D
Methyl 3-(benzo[d][[1,3]]dioxol-5-ylmethyl)-5-oxo-2-(3,4,5-trimethoxyphenyl)tetrahydrofuran-3-carboxylate 4s Prepared following general procedure, using 3,4,5-trimethoxybenzaldehyde (0.98 g, 5 mmol, 1 eq.) and 4-bromobenzo[1,3]dioxole (0.9 mL, 7.5 mmol, 1.5 eq.). Diastereoisomers 4sA and 4sB O O H were obtained in a 79 : 21 ratio as a yellow oil; yield: 0.93 g (42 %); Rf: 0.04 (pentane/diethyl MeO CO2 Me ether mixture (7:3)); 1H NMR (CDCl3): δ = 2.12 (1HB, d, J 13.9), 2.70 (2HA+B, m) 2.82 (2HA+B, MeO m), 3.00 (1HA, d, J 17.8), 3.12 (1HB, d, J 17.7), 3.38 (3HB, s), 3.52 (1HA, d, J 13.9), 3.60-3.86 OMe (18HA+B, m), 4.39 (3HB, s), 5.32 (1HA, s), 5.64 (1HB, s), 5.82-5.90 (4HA+B, m), 6.44 (2HA, s), 6.23-6.71 (8HA+B, m); 13C NMR (CDCl3): δ = 36.2 (2CA+B), 40.5 (2CA+B), 52.3 (1CA), 52.6 (1CB), 56.1 (2CA), 56.3 (1CB), 56.4 (2CB), 58.4 (2CA+B), 60.9 (1CA), 87.4 (2CA+B), 100.8 (1CA), 101.2 (1CB), 105.7 (2CB), 108.0 (2CA), 108.5 (1CB), 108.6 (1CA), 109.9 (2CA+B), 121.4 (1CA), 121.5 (1CB), 129.0 (1CA), 130.2 (1CB), 136.7 (1CA), 137.2 (1CB), 138.9 (1CB), 140.2 (1CA), 145.7 (1CA), 147.0 (1CB), 147.5 (1CA), 148.0 (1CB), 152.7 (2CA), 153.3 (2CB), 170.9 (4CA+B); IR: ν = 730, 1037, 1223, 1361, 1423, 1490, 1505, 1592, 1698 cm-1; MS (EI): m/z = 445 (25), 444 (100), 309 (14), 281 (9), 277 (31), 249 (9), 248 (49), 247 (20), 220 (48), 219 (20), 216 (13), 207 (22), 197 (11), 196 (14), 189 (23), 181 (13), 169 (11), 161 (16), 160 (33), 35 (14); HRMS: m/z (ESI) calcd. for C23H24O9Na (M+22.9898): 467.13125; found: 467.13169. O
AC C
EP
O
Methyl 5-oxo-3-(3,4,5-trimethoxybenzyl)-2-(3,4,5-trimethoxyphenyl)tetrahydrofuran-3-carboxylate 4t Prepared following general procedure, using 3,4,5-trimethoxybenzaldehyde (0.98 g, 5 mmol, 1 eq.) and 3,4,5-trimethoxybromobenzene (1.82 g, 7.5 mmol, 1.5 eq.). Diastereoisomers 4tA and O OMe H 4tB were obtained in a 54 : 46 ratio as a yellow oil; yield: 1.36 g (56 %); Rf: 0.20 MeO (pentane/diethyl ether mixture (7:3)); 1H NMR (CDCl3): δ = 2.14 (1HA, d, J 13.9), 2.66 (1HA, CO2Me d, J 17.6), 2.70 (1HB, d, J 17.5), 2.79 (1HB, d, J 13.7), 2.83 (1HA, d, J 13.9), 2.99 (1HB, d, J MeO OMe 17.5), 3.13 (1HA, d, J 17.6), 3.36 (3HA, s), 3.57 (1HB, d, J 13.7), 3.72-3.85 (39HA+B, m), 5.29 (1HA, s), 5.61 (1HB, s), 6.14 (2HB, s), 6.30 (2HA, s), 6.42 (2HA, s), 6.50 (2HB, s); 13C NMR (CDCl3): δ = 36.0 (1CB), 36.2 (1CA), 38.7 (1CA), 41.3 (1CB), 52.3 (1CA), 52.9 (1CB), 56.1-56.3 (8CA+B), 58.4 (2CA+B), 60.8 (2CB), 60.9 (2CA), 85.5 (1CB), 87.3 (1CA), 102.9 (2CA), 103.5 (2CB), 106.6 (2CB), 106.8 (2CA), 129.5 (2CA+B), 130.2 (1CB), 131.2 (1CA), 137.3 (1CA), 137.4 (1CB), 138.3 (1CB), 138.5 (1CA), 153.1-153.4 (8CA+B), 170.9 (1CA), 172.9 (1CB), 174.4 (2CA+B); IR: ν = 693, 843, 1004, 1122, 1236, 1330, 1422, 1460, 1591, 1709, 1788, 2839, 2942 cm-1; MS (EI): not detected; HRMS: m/z (ESI) calcd. for C25H30O10Na (M+22.9898): 513.17312; found: 513.17331. MeO O
OMe
ACCEPTED MANUSCRIPT Methyl 2-(furan-2-yl)-3-(4-methoxybenzyl)-5-oxotetrahydrofuran-3-carboxylate 4u Prepared following general procedure, using furaldehyde (0.83 mL, 10 mmol, 1 eq.) and 4bromoanisole (1.8 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4uA and 4uB were obtained in a 60 : H 40 ratio as a colorless oil; yield: 1.62 g (49 %); Rf: 0.24 (pentane/diethyl ether mixture (7:3)); 1H CO2Me NMR (CDCl3): δ = 2.38 (1HB, d, J 13.8), 2.67 (1HB, d, J 17.7), 2.94 (1HA, d, J 13.9), 2.96 (1HB, d, J O 13.8), 3.03 (1HA, d, J 18.6), 3.28 (1HB, d, J 17.7), 3.45 (1HA, d, J 18.6), 3.70 (1HA, d, J 13.9), 3.53 (3HA, s), 3.70 (3HB, s), 3.76 (3HA, s), 3.78 (3HB, s), 5.40 (1HA, s), 5.78 (1HB, s), 6.36-6.37 (1HB, m), 6.42 (1HA, m), 6.42 (1HB, m), 6.55 (1HA, m), 6.79 (2HB, d, J 8.7), 6.88 (2HA, d, J 8.7), 6.89 (2HB, d, J 8.7), 7.04 (2HA, d, J 8.7), 7.40 (1HB, m), 7.51 (1HA, m); 13C NMR (CDCl3): δ = 31.7 (1CB), 34.7 (1CA), 37.4 (1CB), 40.8 (1CA), 51.7 (2CA+B), 52.1 (1CA), 57.1 (1CB), 55.1 (1CA), 56.4 (1CB), 79.6 (2CA+B) 110.1-111.6 (4CA+B), 114.0 (2CA), 114.2 (2CB), 126.8 (1CB), 127.5 (1CA), 127.5 (1CA), 171.6 (1CB), 130.1 (2CA), 130.7 (2CB), 143.7 (2CA+B), 148.5 (2CA+B), 158.9 (2CA+B), 171.0 (1CA), 174.3 (1CB); IR: ν = 786, 885, 962, 996, 1030, 1150, 1210, 1440, 1513, 1711, 2955 cm-1; MS (EI): m/z = 330 (25), 281 (5), 234 (5), 210 (12), 209 (100), 207 (5), 206 (23), 181 (11), 175 (8), 147 (15), 146 (24), 145 (7), 131 (6), 122 (31), 121 (48), 91 (9), 78 (5), 77 (7); Anal. calcd. for C18H18O6 (330.11): C 65.45, H 5.49; found: C 65.68, H 5.43. O
OMe
RI PT
O
Methyl 2-hexyl-3-(4-methoxybenzyl)-5-oxotetrahydrofuran-3-carboxylate 4v
Prepared following general procedure, using heptanal (1.4 mL, 10 mmol, 1 eq.) and 4bromoanisole (1.8 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4vA and 4vB were obtained in O a 12 : 88 ratio as a colorless solid, mp: 55°C; yield: 0.94 g (27 %); Rf: 0.19 (pentane/diethyl CO2Me ether mixture (7:3)); 1H NMR (CDCl3): δ = 0.82-0.91 (6HA+B, m), 1.24-1.36 (16HA+B, m,), 1.51-1.70 (4HA+B, m), 2.56 (1HB, d, J 17.4), 2.58 (1HA, d, J 17.5), 2.59 (1HB, d, J 13.9), 2.76 (1HA, d, J 13.9), 2.84 (1HB, d, J 17.4), 2.95 (1HA, d, J 17.5), 3.33 (1HB, d, J 13.9), 3.37 (1HA, d, J 13.9), 3.73 (3HA, s), 3.75 (3HB, s), 3.78 (6HA+B, s), 4.34 (1HA, d, J 8.4), 4.51 (1HB, d, J 9.4), 6.83 (4HA+B, d, J 8.3), 6.98 (2HA, d, J 8.3), 7.03 (2HB, d, J 8.3); 13C NMR (CDCl3): δ = 14.0 (2CA+B), 22.3 (1CA), 22.5 (1CB), 26.2 (1CA), 26.5 (1CB), 29.0 (1CA), 29.2 (1CB), 30.9 (2CA+B), 31.6 (1CA), 31.8 (1CB), 35.6 (1CB), 36.1 (1CA), 39.7 (2CA+B), 52.3 (1CA), 52.6 (1CB), 55.0 (2CA+B), 55.2 (1CB), 55.6 (1CA), 84.9 (1CA), 85.7 (1CB), 114.0 (4CA+B), 127.4 (1CA), 127.5 (1CB), 130.6 (2CB), 130.9 (2CA), 158.8 (2CA+B), 171.9 (1CB), 172.6 (1CA), 174.6 (2CA+B); IR: ν = 837, 961, 1032, 1177, 1248, 1513, 1732, 1782, 2857 cm-1; MS (EI): m/z = 348 (12), 122 (9), 121 (100); Anal. calcd. for C20H28O5 (348.19): C 68.94, H 8.10; found: C 69.25, H 8.48. OMe
M AN U
SC
O
Methyl 3-benzyl-2-methyl-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4w Prepared following general procedure, using acetophenone (0.58 mL, 5 mmol, 1 eq.) and bromobenzene (0.8 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4wA and 4wB were obtained in a 43 : H3C 57 ratio as a colorless oil; yield: 1.34 g (82 %); Rf: 0.04 (pentane/diethyl ether mixture (7:3)); 1H NMR CO2Me (CDCl3): δ = 1.78 (3HB, s), 2.00 (3HA, s), 2.25 (1HB, d, J 13.7), 2.68-2.98 (5HA+B, m), 3.31 (4HA+B, s), 3.74 (1HA, d, J 13.6), 3.81 (3HB, s), 6.97 (2HB, m), 7.15 (2HA, m), 7.25-7.30 (6HA+B, m), 7.37-7.40 (6HA+B, m), 7.47 (2HB, m), 7.67 (2HB, m); 13C NMR (CDCl3): δ = 23.0 (1CA), 25.3 (1CB), 35.7 (1CB), 35.9 (1CA), 37.7 (1CA), 40.5 (1CB), 52.0 (1CA), 52.5 (1CB), 58.9 (1CB), 60.1 (1CA), 89.3 (1CB), 89.3 (1CA), 125.0 (2CA), 126.1 (2CB), 127.2 (1CB), 127.3 (1CA), 128.2 (2CA), 128.3 (2CB), 128.4 (2CA+B), 129.2 (2CA+B), 128.6 (2CB), 128.7 (2CA), 129.8 (2CB), 130.0 (2CA), 130.5 (1CA), 130.8 (1CB), 171.0 (1CA), 171.9 (1CB), 173.7 (1CB), 174.4 (1CA); IR: ν = 699, 766, 949, 1230, 1728, 1778, 2950 cm-1; MS (EI): m/z = 377 (5), 375 (38), 374 (11), 373 (72), 372 (7), 371 (45), 281 (6), 221 (26), 220 (10), 219 (100), 218 (6), 217 (82), 208 (6), 207 (17), 193 (8), 191 (24), 189 (16), 110 (8), 75 (10), 74 (9); HRMS: m/z (ESI) calcd. for C20H20O4Na (M+22.9898): 347.12538; found: 347.12573. O
EP
TE D
O
AC C
Methyl 3-(4-methoxybenzyl)-2-methyl-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4x Prepared following general procedure, using acetophenone (1.12 g, 10 mmol, 1 eq.) and 4bromoanisole (1.8 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4xA and 4xB were obtained in a 40 : 60 ratio as a colorless solid, mp: 143 °C; yield: 3.00 g (85 %); Rf: 0.27 (pentane/diethyl ether mixture (7:3)); Diastereoisomers were separated as described above (Section 4.3). Diastereoisomer 4xA: 1H NMR (CDCl3): δ = 1.95 (3HA, s), 2.62 (1HA, d, J 18.3), 2.77 (1HA, d, J 13.5), 2.90 (1HA, d, J 18.3), 3.31 (3HA, s), 3.65 (1HA, d, J 13.5), 3.77 (3HA, s), 6.80 (2HA, d, J 8.7), 7.02 (2HA, d, J 8.7), 7.27-7.38 (5HA, m); 13 C NMR (CDCl3): δ = 22.9 (1CA), 35.8 (1CA), 37.0 (1CA), 51.9 (1CA), 55.2 (1CA), 60.2 (1CA), 89.3 (1CA), 114.1 (1CA), 125.0 (1CA), 127.6 (1CA), 128.2 (1CA), 128.4 (1CA), 130.9 (1CA), 140.5 (1CA), 158.8 (1CA), 171.0 (1CA), 174.6 (1CA); Diastereoisomer 4xB: 1H NMR (CDCl3): δ = 1.73 (3HB, s), 2.12 (1HB, d, J 13.5), 2.68-2.74 (2HB, m), 3.24 (1HB, d, J 17.5), 3.74 (3HB, s), 3.81 (3HB, s), 6.75 (2HB, d, J 8.7), 6.84 (2HB, d, J 8.7), 7.34-7.59 (3HB, m), 7.60 (2HB, d, J 8.6); 13C NMR (CDCl3): δ = 25.3 (1CB), 35.6 (1CB), 38.9 (1CB), 52.0 (1CB), 52.5 (1CB), 59.0 (1CB), 89.2 (1CB), 114.0 (1CB), 124.6 (1CB), 127.6 (1CB), 128.2 (1CB), 128.3 (1CB), 130.8 (1CB), 139.2 (1CB), 158.7 (1CB), 172.0 (1CB), 173.8 (1CB); IR: ν = 881, 1088, 1141, 1252, 1735, 2973 cm-1; MS (EI): m/z = 355 (7), 354 (33), 235 (13), 234 (100), 233 (5), 207 (11), 206 (78), 203 (5), 202 (21), 175 (15), 174 (13), 160 (10), 147 (21), 146 (36), 135 (6), 131 (7), 121 (67), 115 (5), 91 (7), 77 (9); Anal. calcd. for C21H22O5 (354.15): C 71.17, H 6.26; found: C 71.19, H 6.35.
ACCEPTED MANUSCRIPT
Methyl 3-(3-methoxybenzyl)-2-methyl-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4y Prepared following general procedure, using acetophenone (0.58 mL, 5 mmol, 1 eq.) and 3bromoanisole (0.95 mL, 7.5 mmol, 1.5 éq). Both diastereoisomers 4yA and 4yB were obtained in a OMe H 3C 40 : 60 ratio as a colorless oil; yield: 0.99 g (60 %); Rf: 0.11 (pentane/diethyl ether mixture (7:3)); 1 CO2Me H NMR (CDCl3): δ = 1.78 (3HA, s), 1.99 (3HB, s), 2.23 (1HB, d, J 13.8), 2.70-2.99 (5HA+B, m), 3.33 (1HB, d, J 16.9), 3.35 (3HA, s), 3.69 (1HA, d, J 16.9), 3.70 (3HB, s), 3.75 (3HA, s), 3.87 (3HB, s), 6.52-6.82 (4HB, m), 7.15-7.24 (4HA, m), 7.33-7.70 (10HA+B, m); 13C NMR (CDCl3): δ = 23.0 (1CB), 30.9 (1CA), 35.6 (1CB), 35.9 (1CA), 37.7 (1CA), 40.5 (1CB), 52.0 (1CA), 52.5 (1CB), 55.1 (2CA+B), 58.8 (1CB), 60.1 (1CA), 89.2 (1CB), 89.3 (1CA), 112.6 (2CA+B), 115.4 (1CA), 115.7 (1CB), 122.1 (1CB), 122.2 (1CA), 125.0 (2CA+B), 126.0 (4CA+B), 128.2 (4CA+B), 129.6 (1CB), 129.7 (1CA), 137.3 (1CB), 137.4 (1CA), 139.2 (1CB), 140.4 (1CA), 159.7 (2CA+B), 171.0 (1CB), 171.9 (1CA), 173.6 (1CB), 174.3 (1CA); IR: ν = 579, 701, 768, 949, 1069, 1248, 1731, 1781, 2951 cm-1; MS (EI): m/z = 355 (5), 254 (19), 235 (16), 234 (100), 219 (16), 206 (13), 203 (6), 202 (16), 176 (6), 175 (58), 174 (31), 147 (15), 146 (28), 145 (6), 131 (7), 115 (6), 103 (6), 91 (9); HRMS: m/z (ESI) calcd. for C21H22O5Na (M+22.9898): 377.13594; found: 377.13633. O
RI PT
O
Methyl 3-(2-methoxybenzyl)-2-methyl-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4z
Prepared following general procedure, at room temperature, using acetophenone (0.58 mL, 5 mmol, 1 eq.) and 2-bromoanisole (0.94 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4zA and 4zB were H3C obtained in a 70 : 30 ratio as a yellow oil; yield: 1.54 g (87 %); Rf: 0.12 (pentane/diethyl ether OMe CO2 Me mixture (7:3)); 1H NMR (CDCl3): δ = 1.69 (3HB, s), 1.96 (3HA, s), 2.35 (1HB, d, J 13.7), 2.57 (1HA, d, J 17.5), 2.69 (1HB, d, J 17.9), 2.79 (1HB, d, J 13.7), 2.81 (1HA, d, J 17.5), 3.21 (1HB, d, J 17.9), 3 31 (3HA, s), 3.34 (1HA, d, J 13.0), 3.40 (1HA, d, J 13.0), 3.74 (3HB, s), 3.78 (3HB, s), 3.81 (3HA, s), 6.74-6.84 (5HA+B, m), 7.02 (1HA, m), 7.13-7.17 (2HA+B, m), 7.28-7.31 (5HA+B, m), 7.39-7.42 (3HA+B, m), 7.55 (2HB, m); 13C NMR (CDCl3): δ = 23.0 (1CA), 25.3 (1CB), 30.5 (1CA), 33.4 (1CB), 35.3 (1CA), 35.6 (1CB), 51.9 (1CA), 52.4 (1CB), 55.1 (1CB), 55.2 (1CA), 59.2 (1CB), 60.3 (1CA), 89.1 (1CB), 89.2 (1CA), 110.4 (1CB), 110.5 (1CA), 120.6 (1CB), 120.7 (1CA), 124.4 (1CB), 124.5 (1CA), 125.1 (2CA), 126.2 (2CB), 128.0 (2CA), 128.1 (2CB), 128.2 (2CA+B), 128.3 (1CA), 128.6 (1CB), 130.6 (1CB), 130.9 (1CA), 139.5 (1CB), 140.8 (1CA), 157.5 (1CB), 157.6 (1CA), 171.4 (1CB), 172.4 (1CA), 174.1 (1CB), 175.1 (1CA); IR: ν = 700, 756, 900, 1007, 1214, 1244, 1439, 1494, 1729, 1781, 2950 cm-1; MS (EI): m/z = 353 (22), 235 (12), 234 (100), 206 (24), 203 (11), 202 (15), 187 (9), 175 (48), 174 (60), 147 (11), 146 (18), 145 (10), 132 (9), 131 (39), 126 (64), 121 (54), 115 (12), 93 (13), 91 (40), 77 (9); HRMS: m/z (ESI) calcd. for C21H22O5Na (M+22.9898): 377.13594; found: 377.13626. O
M AN U
SC
O
Methyl 3-(4-methoxybenzyl)-5-oxo-2-phenyl-2-(trifluoromethyl)tetrahydrofuran-3-carboxylate 4aa Prepared following general procedure, using 2,2,2-trifluoroacetophenone (1.36 mL, 10 mmol, 1 eq.) and 4-bromoanisole (1.8 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4aaA and 4aaB were F3C obtained in a 88 : 12 ratio as a colorless oil; yield: 2.20 g (54 %); Rf: 0.72 (pentane/diethyl ether CO2 Me mixture (7:3)); 1H NMR (CDCl3): δ = 2.04 (1HB, d, J 13.9), 2.71 (1HB, d, J 17.5), 2.78 (1HA, d, J 18.5), 3.03 (1HB, d, J 17.5), 3.02 (1HB, d, J 13.9), 3.10 (3HA, s), 3.17 (1HA, d, J 13.5), 3.56 (1HA, d, J 18.5), 3.69 (3HB, s), 3.76 (3HA, s), 3.87 (1HA, d, J 13.5), 3.88 (3HB, s), 6.76 (2HB, d, J 8.6), 6.80 (2HA, d, J 8.6), 6.86 (2HB, d, J 8.5), 7.15 (2HA, d, J 8.5), 7.42-7.48 (6HA+B, m), 7.61-7.63 (4HA+B, m); 13C NMR (CDCl3): δ = 34.0 (1CB), 34.6 (1CA), 36.5 (1CB), 39.2 (1CA), 51.3 (1CA), 52.2 (1CB), 54.1 (1CA), 55.2 (1CB), 59.1 (2CA+B), 86.9 (1CA, q, J 28.6), 87.5 (1CB, q, J 28.8), 113.0 (2CA), 113.3 (2CB), 123.2 (2CA+B, q, J 288.0), 124.9, (2CB), 125.2 (2CA), 125.9 (1CB), 126.4 (1CA), 127.3, (4CA+B), 128.8, (2CA+B), 129.0 (1CB), 129.5 (1CA), 130.3 (2CA), 130.4 (2CB), 157.9 (1CA), 158.0 (1CB), 168.5 (1CB), 168.8 (1CA), 170.7 (1CA), 170.9 (1CB); 19F NMR (CDCl3): δ = -72.0 (6FA+B); IR: ν = 699, 711, 1028, 1166, 1252, 1513, 1738, 1812, 2957 cm-1; MS (EI): m/z = 408 (13), 233 (6), 205 (5), 146 (6), 145 (6), 122 (8), 121 (100), 91 (6), 77 (6); Anal. calcd. for C21H19F3O5 (408.12): C 61.76, H 4.59; found: C 61.41, H 4.67. O
OMe
AC C
EP
TE D
O
Methyl 3-benzyl-2-ethyl-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4ab Prepared following general procedure, using propiophenone (1.34 mL, 10 mmol, 1 eq.) and bromobenzene (1.9 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4abA and 4abB were obtained in a H3 C-CH2 81 : 19 ratio as a colorless solid, mp: 124°C; yield: 1.76 g (52%); Rf: 0.26 (pentane/diethyl ether CO2Me mixture (7:3)); 1H NMR (CDCl3): δ = 0.85 (3HA, t, J 7.2), 0.91 (3HB, t, J 7.2), 2.10 (1HA, m), 2.15 (1HA, m), 2.25 (1HA, d, J 13.8), 2.29 (1HB, m), 2.55 (1HB, m), 2.76 (1HB, d, J 18.2), 2.80 (1HA, d, J 18.2), 2.85 (1HA, d, J 13.8), 2.89 (1HB, d, J 18.2), 2.99 (1HB, d, J 13.7), 3.35 (3HB, s), 3.40 (1HA, d, J 18.2), 3.73 (1HB, d, J 13.7), 3.89 (3HA, s), 7.01 (1HA, dd, J 1.9, 7.2), 7.20 (1HB, dd, J 1.6, 8.0), 7.21-7.50 (17HA+B, m), 7.70 (1HA, d, J 7.8); 13 C NMR (CDCl3): δ = 8.1 (1CA), 8.4 (1CB), 27.9 (1CB), 30.2 (1CA), 35.7 (1CA), 36.4 (1CB), 37.1 (1CB), 40.7 (1CA), 51.9 (1CB), 52.5 (1CA), 59.1 (1CA), 60.7 (1CB), 92.4 (1CA), 92.4 (1CB), 125.6 (1CB), 126.6 (1CA), 127.2-128.9 (16CA+B), 129.8 (1CA), 130.0 (1CB), 135.8 (1CA), 136.0 (1CB), 136.8 (1CA), 137.9 (1CB), 171.2 (1CB), 171.9 (1CA), 173.7 (1CA), 174.3 (1CB); IR: ν = 688, 749, 948, 962, 1212,1723, 1792, 2944 cm-1; MS (EI): m/z = 309 (23), 277 (7), 263 (7), 249 (13), 205 (20), 204 (100), 177 (9), 176 (73), 173 (7), 172 (53), 145 (16), 144 (20), 134 (17), 117 (45), 116 (39), 115 (42), 105 (38), 91 (38), 77 (19), 65 (8); Anal. calcd. for C21H22O4 (338.15): C 74.54, H 6.55; found: C 74.39, H 6.72. O
O
ACCEPTED MANUSCRIPT
Methyl 2-ethyl-3-(4-methoxybenzyl)-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4ac Prepared following general procedure, using propiophenone (0.67 mL, 5 mmol, 1 eq.) and 4bromoanisole (1.8 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4acA and 4acB were obtained in a H3 C-CH 2 40 : 60 ratio as a yellow oil; yield: 0.76 g (41 %); Rf: 0.57 (pentane/diethyl ether mixture (7:3)); 1 CO2 Me H NMR (CDCl3): δ = 0.79 (3HB, t, J 7.0), 0.81 (3HA, t, J 7.0), 2.00 (1HB, m), 2.05 (1HB, m), 2.13 (1HB, d, J 13.9), 2.23 (1HA, m), 2.45 (1HA, m), 2.63-2.73 (3HA+B, m), 2.81-2.85 (2HA+B, m), 3.263.31 (4HA, m), 3.63 (1HA, d, J 13.3), 3.73 (3HB, s), 3.75 (3HA, s), 3.80 (3HB, s), 6.74 (2HB, d, J 8.4), 6.79 (2HA, d, J 8.4), 6.84 (2HB, d, J 8.4), 7.03 (2HA, d, J 8.4), 7.35-7.44 (8HA+B, m), 7.58 (2HB, d, J 7.5); 13C NMR (CDCl3): δ = 8.0 (1CB), 8.3 (1CA), 27.8 (1CA), 30.2 (1CB), 34.9 (1CA), 35.7 (2CA+B), 39.8 (1CB), 51.9 (1CA), 52.5 (1CB), 55.1 (1CB), 55.2 (1CA), 59.2 (1CB), 60.8 (1CA), 92.3 (1CA), 92.4 (1CB), 114.0 (4CA+B), 125.6 (2CA), 126.6 (2CB), 127.6 (1CA), 127.9 (1CB), 128.0 (1CA), 128.1 (1CB), 128.2 (2CB), 128.4 (2CA), 130.8 (2CB), 131.0 (2CA), 136.9 (1CB), 137.9 (1CA), 158.7 (2CA+B), 171.2 (1CA), 171.9 (1CB), 173.8 (1CB), 174.4 (1CA); IR: ν = 699, 752, 975, 1223, 1249, 1296, 1512, 1730, 1780, 2950 cm-1; MS (EI): m/z = 369 (8), 368 (30), 235 (7), 234 (59), 207 (20), 206 (20), 202 (15), 175 (11), 174 (6), 160 (8), 147 (16), 146 (27), 135 (10), 122 (8), 121 (100), 115 (6), 103 (7), 91 (14), 77 (13); HRMS: m/z (ESI) calcd. for C22H24O5Na (M+22.9898): 391.15159; found: 391.15182. O
OMe
RI PT
O
Methyl 2-methyl-5-oxo-2-phenyl-3-(4-trifluoromethyl)benzyl)tetrahydrofuran-3-carboxylate 4ad
Prepared following general procedure, using acetophenone (0.58 mL, 5 mmol, 1 eq.) and 4trifluorobromobenzene (1.04 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4adA and 4adB were O H 3C obtained in a 28 : 72 ratio as a yellow oil; yield: 0.43 g (22 %); Rf: 0.30 (pentane/diethyl ether CO2Me mixture (7:3)); 1H NMR (CDCl3): δ = 1.72 (3HB, s), 1.94 (3HA, s), 2.23 (1HB, d, J 13.7), 2.56 (1HA, d, J 17.6), 2.61 (1HB, d, J 18.1), 2.82 (1HB, d, J 13.7), 2.91 (1HA, d, J 13.7), 3.24 (1HA, d, J 17.6), 3.28 (3HA, s), 3.26 (1HB, d, J 18.1), 3.74 (1HA, d, J 13.7), 3.80 (3HB, s), 7.04 (2HB, d, J 8.0), 7.22 (2HA, d, J 8.0), 7.297.47 (10HA+B, m), 7.51 (2HA, d, J 8.0), 7.54 (2HB, d, J 8.0); 13C NMR (CDCl3): δ = 23.1 (1CA), 25.3 (1CB), 35.6 (1CB), 35.8 (1CA), 37.6 (1CA), 40.1 (1CB), 52.2 (1CB), 52.7 (1CA), 58.7 (1CB), 59.9 (1CA), 89.3 (2CA+B), 124.9 (2CA, q, J 3.8), 125.5 (2CA+B), 125.5 (2CB, q, J 3.8), 126.0 (4CA+B), 128.4 (2CB), 128.5 (2CA), 129.5 (1CA, q, J 273.3), 129.6 (1CB, q, J 273.2), 130.2 (4CA+B), 130.3 (2CA+B, q, J 31.0), 139.0 (2CA+B), 140.1 (2CA+B), 170.1 (1CA), 171.6 (1CB), 173.2 (1CB), 173.9 (1CA); 19F NMR (CDCl3): δ = -62.6 (6FA+B); IR: ν = 700, 768, 1067, 1115, 1324, 1731, 1781, 2954 cm-1; MS (EI): m/z = 373 (6), 273 (13), 272 (100), 245 (11), 244 (74), 240 (20), 213 (15), 212 (11), 202 (40), 185 (21), 184 (28), 175 (5), 165 (13), 115 (12), 105 (8), 77 (6); HRMS: m/z (ESI) calcd. for C21H19F3O4Na (M+22.9898): 415.11276; found: 415.11298. CF3
M AN U
SC
O
Methyl 2-methyl-5-oxo-2-phenyl-3-(3-trifluoromethyl)benzyl)tetrahydrofuran-3-carboxylate 4ae Prepared following general procedure, using acetophenone (0.58 mL, 5 mmol, 1 eq.) and 3trifluorobromobenzene (1.04 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4aeA and 4aeB were obtained in a 40 : 60 ratio as a colorless oil; yield: 0.44 g (23 %); Rf: 0.20 (pentane/diethyl ether CO2Me mixture (7:3)); 1H NMR (CDCl3): δ = 1.71 (3HB, s), 1.92 (3HA, s), 2.23 (1HB, d, J 13.7), 2.60 (1HB, d, J 18.1), 2.62 (1HA, d, J 17.6), 2.78 (1HB, d, J 13.7), 2.87 (1HA, d, J 17.6), 2.92 (1HA, d, J 13.3), 3.23 (3HA, s), 3.27 (1HB, d, J 18.1), 3.64 (1HA, d, J 13.3), 3.76 (3HB, s), 7.11-7.57 (18HA+B, m); 13C NMR (CDCl3): δ = 23.1 (1CB), 25.2 (1CA), 35.6 (1CB), 36.1 (1CA), 37.4 (1CA), 42.8 (1CB), 52.0 (1CA), 52.6 (1CB), 58.8 (1CB), 60.1 (1CA), 89.2 (1CB), 89.3 (1CA), 124.3 (1CB, q, J 3.9), 124.9 (2CA+B), 125.3 (1CA, q, J 272.3), 125.5 (1CA, q, J 3.8), 125.6 (1CB, q, J 276.5), 126.0 (2CA+B), 126.4 (1CA, q, J 3.7), 126.6, (1CB, q, J 3.7), 128.2 (2CA), 128.4 (2CB), 129.1 (1CB), 129.2 (1CA), 131.3 (1CA, q, J 31.6), 131.4 (1CA, q, J 32.2), 133.4 (2CA+B), 136.9 (4CA+B), 139.0 (1CB), 140.1 (1CA), 170.7 (1CA), 171.6 (1CB), 173.2 (1CB), 173.8 (1CA); 19F NMR (CDCl3): δ = -61.5 (6FA+B); IR: ν = 573, 956, 1168, 1286, 1736, 1780, 2350, 2791, 2926, 2955 cm-1; MS (EI): m/z = 273 (16), 272 (100), 252 (9), 245 (10), 244 (72), 240 (13), 213 (15), 212 (13), 203 (8), 202 (47), 185 (26), 184 (25), 175 (6), 165 (14), 159 (6), 115 (16), 105 (8), 77 (9); HRMS: m/z (ESI) calcd. for C21H19F3O4Na (M+22.9898): 415.11276; found: 415.11292. CF3
AC C
EP
H 3C
TE D
O
O
Methyl 2-methyl-5-oxo-2-phenyl-3-(2-trifluoromethyl)benzyl)tetrahydrofuran-3-carboxylate 4af Prepared following general procedure, at room temperature, using acetophenone (0.58 mL, 5 mmol, 1 eq.) and 2-trifluorobromobenzene (1.4 mL, 10 mmol, 2 eq.). Both diastereoisomers 4afA and 4afB H 3C were obtained in a 63 : 37 ratio as a colorless oil; yield: 0.30 g (15 %); Rf: 0.38 (pentane/diethyl ether CF3 CO2Me mixture (7:3)); 1H NMR (CDCl3): δ = 1.61 (3HB, s), 1.83 (3HA, s), 2.40 (1HB, d, J 18.3), 2.47 (1HA, d, J 17.6), 2.75 (1HB, d, J 15.5), 2.90-2.95 (2HA, m), 3.26 (3HA, s), 3.38-3.41 (2HA+B, m), 3.84 (1HB, d, J 18.3), 3.90 (3HB, s), 6.90 (1HB, m), 7.07 (1HA, m), 7.24-7.35 (12HA+B, m), 7.42 (2HA, m), 7.55 (2HB, d, J 7.7); 13C NMR (CDCl3): δ = 23.7 (1CA), 25.4 (1CB), 32.0 (1CA), 35.5 (1CB), 35.8 (1CB), 36.3 (1CA), 52.4 (1CA), 53.0 (1CB), 58.1 (1CA), 59.4 (1CB), 89.3 (1CB), 89.9 (1CA), 125.0 (4CA+B), 125.1 (1CB, q, J 272.3), 125.9 (1CA, q, J 272.4), 126.0 (2CA+B), 126.7 (2CA+B), 127.1 (2CA+B, q, J 6.0), 128.1 (2CA+B, q, J 6.0), 128.3 (2CA), 128.3 (2CB), 129.1 (1CA), 129.2 (1CB), 129.3 (2CA+B, q, J 32.1), 132.0 (1CB), 132.3 (1CA), 138.9 (1CB), 140.1 (1CA), 172.2 (1CA), 173.0 (1CB), 173.3 (1CB), 173.8 (1CA); 19F NMR (CDCl3): δ = -58.5 (6FA+B); IR: ν = 701, 767, 1001, 1310, 1730, 1784, 2954 cm-1; MS (EI): m/z = 273 (15), 272 (100), 252 (12), 249 (41), 240 (36), 213 (10), 212 (8), 204 (21), 203 (6), 202 (36), 193 (23), 185 (7), 184 (6), 177 (6), 173 (27), 165 (14), 164 (8), 115 (8), 105 (6), 77 (6); HRMS: m/z (ESI) calcd. for C21H19F3O4Na (M+22.9898): 415.11276; found: 415.11255. O
O
ACCEPTED MANUSCRIPT Methyl 3-(4-methoxycarbonylbenzyl)-2-methyl-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4ag Prepared following general procedure, using acetophenone (0.58 mL, 5 mmol, 1 eq.) and 4methylbromobenzoate (1.60 g, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4agA and 4agB were H 3C obtained in a 35 : 65 ratio as a yellow oil; yield: 0.880 g (46%); Rf: 0.55 (pentane/diethyl ether CO2Me mixture (7:3)); 1H NMR (CDCl3): δ = 1.76 (3HB, s), 1.96 (3HA, s), 2.25 (1HB, d, J 13.7), 2.60-2.69 (2HA+B, m), 2.80-2.93 (3HA+B, m), 3.25-3.30 (4HA, m), 3.73 (1HA, d, J 13.6), 3.80 (3HB, s), 3.87 (3HB, s), 3.88 (3HA, s), 7.01 (2HB, d, J 8.2), 7.19 (2HA, d, J 8.2), 7.25-7.45 (4HA+B, m), 7.37-7.40 (4HA, m), 7.59 (2HB, d, J 7.4), 7.89 (2HB, d, J 8.2), 7.67 (2HA, d, J 8.2); 13C NMR (CDCl3): δ = 23.1 (1CA), 25.3 (1CB), 35.7 (1CB), 35.9 (1CA), 37.7 (1CA), 40.4 (1CB), 52.1 (2CA+B), 52.7 (2CA+B), 58.8 (1CB), 59.8 (1CA), 89.4 (1CB), 89.5 (1CA), 124.6 (2CA), 124.9 (2CB), 126.0 (2CB), 127.2 (2CA), 128.2 (4CA+B), 129.2 (1CA), 129.3 (1CB), 129.8 (4CA+B), 129.9 (1CB), 130.2 (1CA), 139.0 (1CB), 140.1 (1CA), 141.2 (2CA+B), 166.7 (2CA+B), 170.7 (1CA), 171.6 (1CB), 173.6 (1CB), 174.3 (1CA); IR: ν = 702, 764, 950, 1109, 1221, 1280, 1716, 1781, 2953 cm-1; MS (EI): m/z = 351 (11), 281 (6), 263 (17), 262 (100), 247 (7), 235 (13), 234 (91), 230 (28), 207 (28), 203 (30), 202 (19), 192 (21), 175 (17), 174 (17), 171 (10), 143 (17), 131 (7), 121 (7), 115 (16), 91 (8); HRMS: m/z (ESI) calcd. for C22H22O6Na (M+22.9898): 405.13086; found: 405.13120. CO2Me
O
RI PT
O
Methyl 3-benzyl-2-methyl-5-oxo-2-(3,4,5-trimethoxyphenyl)tetrahydrofuran-3-carboxylate 4ah
Prepared following general procedure, using 3,4,5-trimethoxyacetophenone (1.05 g, 5 mmol, 1 eq.) and bromobenzene (0.8 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4ahA and 4ahB were H3 C MeO obtained in a 51 : 49 ratio as a yellow oil ; yield: 2.05 g (99 %); Rf: 0.14 (pentane/diethyl ether CO2 Me mixture (7:3)); 1H NMR (CDCl3): 1.74 (3HB, s), 2.06 (3HA, s), 2.41 (1HA, d, J 13.6), 2.68 (1HA, d, J MeO OMe 17.8), 2.73 (1HB, d, J 17.8), 2.85 (1HA, d, J 13.6), 2.93 (1HB, d, J 17.8), 3.07 (1HB, d, J 13.4), 3.30 (4HA+B, m), 3.63 (1HB, d, J 13.4), 3.75-4.01 (21HA+B, m), 5.37 (4HA+B, s), 6.69 (1HB, s), 6.96 (2HB, m), 7.03 (2HA, m), 7.23-7.25 (5HA+B, m); 13C NMR (CDCl3): 23.7 (1CB), 25.7 (1CA), 36.2 (1CA), 37.9 (1CB), 38.6 (1CB), 40.5 (1CA), 52.3 (1CB), 52.9 (1CA), 56.6 (2CA), 56.7 (2CB), 59.9 (1CA), 60.0 (2CA+B), 61.4 (1CB), 89.6 (1CA), 89.7 (1CB), 104.0 (2CA),105.0 (2CB), 127.8 (1CB), 127.9 (1CA), 129.3 (4CA+B), 130.7 (2CB), 130.9 (2CA), 136.0 (2CA+B), 137.3 (1CA), 137.8 (1CB), 139.0 (2CA+B), 154.0 (2CA), 154.2 (2CB), 170.8 (1CA), 172.4 (1CB), 173.4 (1CA), 174.1 (1CB); IR: ν = 590, 704, 839, 1118, 1219, 1247, 1334, 1418, 1454, 1516, 1592, 1727, 2943 cm-1; MS (EI): m/z = 415 (12), 414 (45), 212 (8), 211 (45), 210 (100), 204 (9), 196 (6), 195 (40), 176 (13), 172 (7), 169 (14), 117 (8), 116 (8), 115 (11), 91 (5); HRMS: m/z (ESI) calcd. for C23H26O7Na (M+22.9898): 437.15707; found: 437.15714. O
M AN U
SC
O
Methyl 3-(4-(methoxybenzyl)-2-methyl-5-oxo-2-(3,4,5-trimethoxyphenyl)tetrahydrofuran-3-carboxylate 4ai Prepared following general procedure, using 3,4,5-trimethoxyacetophenone (1.05 g, 5 mmol, 1 eq.) and 4-bromoanisole (0.9 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4aiA and 4aiB were O H3 C obtained in a 62 : 38 ratio as a yellow oil; yield: 1.972 g (89 %); Rf: 0.20 (pentane/diethyl ether MeO CO2Me mixture (7:3)); 1H NMR (CDCl3): δ = 1.63 (3HA, s), 1.85 (3HB, s), 2.49-2.56 (2HA+B, m), 2.65MeO 2.70 (2HA+B, m), 2.75-2.85 (2HA+B, m), 3.22 (1HA, d, J 18.1), 3.28 (3HB, s), 3.56 (1HB, d, J 13.3), OMe 3.67-3.85 (27HA+B, m), 6.45 (2HB, s), 6.68-6.82 (6HA, m), 6.92-6.95 (2HB, m), 7.15-7.18 (2HB, m); 13C NMR (CDCl3): δ = 23.1 (1CB), 25.9 (1CA), 35.6 (1CA), 35.8 (1CB), 37.2 (1CB), 39.4 (1CA), 52.1 (1CB), 52.5 (1CA), 52.1 (1CA), 52.5 (1CB), 55.2 (2CA+B), 56.3 (4CA+B), 59.1 (2CA+B), 89.3 (1CB), 89.5 (1CA), 102.7 (2CA), 103.6 (2CB), 114.0 (2CA), 114.1 (2CB), 127.4 (2CA+B), 127.5 (2CA+B), 130.8 (2CA), 130.9 (2CB), 134.9 (1CA), 136.2 (1CB), 152.9 (2CA), 153.0 (2CB), 158.8 (2CA+B), 171.2 (1CB), 172.0 (1CA), 173.9 (1CA), 174.7 (1CB); IR: ν = 838, 1123, 1245, 1335, 1416, 1511, 1591, 1697, 2839, 2942 cm-1; MS (EI): m/z = 445 (20), 444 (81), 288 (8), 234 (34), 233 (25), 212 (11), 211 (42), 210 (100), 207 (10), 206 (57), 205 (11), 202 (13), 195 (50), 175 (10), 169 (17), 147 (16), 146 (25), 145 (8), 135 (9), 121 (18); HRMS: m/z (ESI) calcd. for C24H28O8Na (M+22.9898): 467.16764; found: 467.16788. OMe
AC C
EP
TE D
O
Methyl 3-benzyl-2-methyl-5-oxo-2-(3-(trifluoromethyl)phenyl)tetrahydrofuran-3-carboxylate 4aj Prepared following general procedure, using 3-trifluoroacetophenone (0.75 mL, 5 mmol, 1 eq.) and bromobenzene (0.8 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4ajA and 4ajB were obtained in a H3C 45 : 55 ratio as a yellow oil; yield: 1.07 g (51 %); Rf: 0.28 (pentane/diethyl ether mixture (7:3)); 1H F3C CO2Me NMR (CDCl3): δ = 1.77 (3HB, s), 2.01 (3HA, s), 2.23 (1HB, d, J 13.7), 2.69-2.76 (3HA+B, m), 2.862.92 (2HA, m), 3.35 (3HA, s), 3.36 (1HB, d, J 18.1), 3.72 (1HA, d, J 13.2), 3.85 (3HB, s), 6.95 (2HB, d, J 7.5), 7.13 (2HA, d, J 6.4), 7.24-7.31 (6HA+B, m), 7.54-7.68 (6HA+B, m), 7.91 (1HB, d, J 7.8), 7.97 (1HB, s); 13C NMR (CDCl3): δ = 23.1 (1CB), 25.4 (1CA), 35.3 (1CB), 35.8 (1CA), 37.7 (1CA), 40.6 (1CB), 52.1 (1CA), 52.7 (1CB), 58.8 (1CB), 60.1 (1CA), 88.6 (1CB), 88.7 (1CA), 120.0 (1CB, q, J 3.8), 122.1 (1CA, q, J 3.8), 123.1 (1CA, q, J 3.6), 125.1 (1CB, q, J 3.6), 127.4 (2CA+B), 128.4 (2CA+B, q, J 297.7), 128.7 (2CA), 128.8 (2CB), 128.9 (2CA+B), 129.1 (2CA+B), 129.7 (2CB), 129.9 (2CA), 130.9 (2CA+B, q, J 32.2), 135.2 (1CA), 135.5 (1CB), 140.3 (1CB), 141.7 (1CA), 170.7 (1CA), 171.6 (1CB), 173.0 (1CB), 173.7 (1CA); 19F NMR (CDCl3): δ = -62.8 (6FA+B); IR: ν = 702, 806, 1007, 1071, 1167, 1221, 1384, 1714, 1731, 1787, 2954 cm-1; MS (EI): m/z = 392 (6), 373 (8), 342 (10), 332 (6), 313 (6), 205 (9), 204 (78), 203 (37), 177 (19), 176 (100), 175 (9), 173 (24), 172 (66), 145 (41), 144 (39), 134 (23), 117 (55), 116 (68), 115 (48), 91 (26); HRMS: m/z (ESI) calcd. for C21H19F3O4Na (M+22.9898): 415.11276; found: 415.11303. O
O
ACCEPTED MANUSCRIPT Methyl 3-(4-methoxybenzyl)-2-methyl-5-oxo-2-(3-(trifluoromethyl)phenyl)tetrahydrofuran-3-carboxylate 4ak Prepared following general procedure, using 3-trifluoroacetophenone (0.75 mL, 5 mmol, 1 eq.) and 4-bromoanisole (0.9 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4akA and 4akB were H3C obtained in a 44 : 56 ratio as a yellow oil; yield: 1.09 g (52 %); Rf: 0.26 (pentane/diethyl ether F3C CO2Me mixture (7:3)); 1H NMR (CDCl3): δ = 1.70 (3HB, s), 2.10 (4HA+B, m), 2.56-2.84 (4HA+B, m), 3.27 (4HA, m), 3.49-3.61 (2HA+B, m), 3.70 (3HA, s), 3.72 (3HB, s), 3.79 (3HB, s), 6.71-6.81 (6HA+B, m), 6.97 (2HB, m), 7.44-7.84 (8HA+B, m); 13C NMR (CDCl3): δ = 23.1 (1CB), 25.4 (1CA), 35.3 (1CA), 35.8 (1CB), 36.9 (1CA), 39.8 (1CB), 52.0, (2CA+B), 52.8 (1CA), 55.2 (1CB), 58.9 (1CB), 60.2 (1CA), 88.6 (1CB), 88.7 (1CA), 114.1, (4CA+B), 122.0 (1CB, q, J 3.8), 123.1 (1CA, q, J 3.8), 124.6 (1CA, q, J 3.7), 125.1 (1CB, q, J 3.7), 127.0 (1CB), 127.3 (1CA), 128.1 (1CA), 128.3 (1CB), 128.5, (2CA+B, q, J 272.8), 128.7 (1CA), 129.0 (1CB), 129.6 (1CB, q, J 36.9), 130.7 (2CB), 130.9 (2CA), 131.1 (1CA, q, J 36.9 Hz), 140.4 (1CB), 141.8 (1CA), 158.9, (2CA+B), 170.8 (1CA), 171.7 (1CB), 173.1 (1CB), 173.8 (1CA); 19F NMR (CDCl3): δ = -62.8 (6FA+B); IR: ν = 680, 804, 1072, 1119, 1165, 1249, 1331, 1513, 1732, 1786, 2954 cm-1; MS (EI): m/z = 423 (5), 422 (24), 234 (8), 233 (6), 206 (15), 175 (6), 147 (8), 146 (13), 145 (6), 122 (10), 121 (100), 91 (7), 77 (5); HRMS: m/z (ESI) calcd. for C22H21F3O5Na (M+22.9898): 445.12333; found: 445.12363. O
OMe
SC
Methyl 3-benzyl-2,2-dimethyl-5-oxotetrahydrofuran-3-carboxylate 4al
RI PT
O
Prepared following general procedure, using acetone (0.76 mL, 10 mmol, 1 eq.) and bromobenzene (1.9 mL, 15 mmol, 1.5 eq.). Compound 4al was obtained as a colorless solid, mp: 106°C; yield: 1.49 g (66 H3C %); Rf: 0.33 (pentane/diethyl ether mixture (7:3)); 1H NMR (CDCl3): δ = 1.36 (3H, s), 1.64 (3H, s), 2.59 H3C CO2Me (1H, d, J 18.1), 2.65 (1H, d, J 13.4), 3.07 (1H, d, J 18.1), 3.48 (1H, d, J 13.4), 3.75 (3H, s), 7.04 (2H, d, J 8.0), 7.23-7.26 (3H, m); 13C NMR (CDCl3): δ = 22.4 (1C), 24.9 (1C), 35.2 (1C), 38.2 (1C), 52.4 (1C), 57.8 (1C), 86.4 (1C), 127.4 (1C), 128.8 (1C), 129.6 (1C), 135.7 (1C), 171.8 (1C), 173.9 (1C); IR: ν = 794, 1017, 1147, 1204, 1256, 1322, 1437, 1725, 1775, 2954 cm-1; MS (EI): m/z = 263 (7), 262 (25), 247 (34), 231 (14), 230 (100), 205 (6), 204 (53), 203 (53), 202 (39), 201 (8), 187 (8), 186 (5), 185 (9), 184 (14), 177 (7), 176 (50), 175 (12), 172 (19), 171 (6), 159 (7), 157 (15), 156 (7), 145 (31), 144 (29), 143 (18), 134 (12), 117 (44), 116 (47), 115 (43), 92 (6), 91 (65), 65 (8); Anal. calcd. for C15H18O4 (262.12): C 68.68, H 6.92; found: C 68.79, H 6.99. O
M AN U
O
Methyl 4-benzyl-2-oxo-1-oxaspiro[4.5]decane-4-carboxylate 4am
Prepared following general procedure, using cyclohexanone (1.04 mL, 10 mmol, 1 eq.) and bromobenzene (1.9 mL, 15 mmol, 1.5 eq.). Compound 4am was obtained as a colorless oil; yield: 0.42 g (14 %); Rf: 0.37 (pentane/diethyl ether mixture (7:3)); 1H NMR (CDCl3): δ = 1.17-2.12 (10H, m,), 2.59 CO2Me (1H, d, J 18.1), 2.63 (1H, d, J 13.3), 3.07 (1H, d, J 18.1), 3.46 (1H, d, J 13.3), 3.76 (3H, s), 7.05 (2H, d, J 8.0), 7.26-7.27 (3H, m); 13C NMR (CDCl3): δ = 21.8 (1C), 22.3 (1C), 25.0 (1C), 30.3 (1C), 33.1 (1C), 35.2 (1C), 37.7 (1C), 52.3 (1C), 58.4 (1C), 87.7 (1C), 127.3 (1C), 128.7 (1C), 129.8 (1C), 135.8 (1C), 171.1 (1C), 174.1 (1C); IR: ν = 701, 892, 1056, 1066, 1229, 1251, 1394, 1406, 1734, 2361, 2901, 2987 cm-1; MS (EI): m/z = 303 (5), 302 (29), 271 (17), 270 (100), 243 (6), 242 (9), 241 (10), 225 (7), 224 (8), 211 (21), 205 (8), 204 (56), 177 (8), 176 (56), 173 (6), 172 (27), 145 (16), 144 (15), 134 (8), 117 (22), 116 (26), 115 (21), 91 (42), 65 (6); Anal. calcd. for C18H22O4 (302.15): C 71.50, H 7.33; found: C 71.35, H 7.45. O
AC C
EP
TE D
O
ACCEPTED MANUSCRIPT
4.5. Biological evaluations
M AN U
SC
RI PT
The human cell lines were obtained from ATCC, except when otherwise stated and grown in D-MEM or in RPMI medium supplemented with 10% fetal calf serum, in the presence of penicilline, streptomycine and fungizone in 75 cm² flask under 5% CO2 at 37°C. Cells were plated in 96-well tissue culture plates in 200µl medium and treated 24 h later with 2 µl stock solution of compounds 4a-am dissolved in DMSO using a Biomek 3000 (BeckmanCoulter) in sterile conditions. Controls received the same volume of DMSO (1% final volume). After 72 h exposure, MTS reagent (Promega) was added and incubated for 3 h at 37°C: the absorbance was monitored at 490 nm and results expressed as the inhibition of cell proliferation calculated as the ratio [(1-(OD490 treated/OD490 control))×100] in triplicate experiments [44]. Necrosis was estimated through the release of LDH from HL60 cells in the culture medium. 25 µL of culture medium was added with 25 µL Cytotox-ONE reagent (Promega) and kept in the dark at room temperature for 20 min. Fluorescence was recorded (exc 560 nm, em 590 nm) and results are expressed as the residual activity in the presence of chemicals compared to activity in the presence of vehicle alone. Apoptotic and necrotic cells were analyzed in flow cytometry using HL60 cells. Double-staining for phosphatidyl serine and DNA was performed by addition of staining solution containing annexin V-PE (Bender MedSystems) and 7-AAD (Enzo Biomol). Cellular fluorescence was measured by flow cytometry with a Guava EasyCyte plus cytometer (Millipore). HL60 cells were exposed to compounds for 24 and 48 h at 37°C under 5% CO2. Cells were stained with propidium iodide before be analyzed by flow cytometry with a Guava Easycyte cytometer (Millipore). Cell populations were quantified using Modfit LT (Verity Software House). Caspase activities were assayed in HL60 cell after a 48 h treatment. Cell lysates were added with DEVD-AMC, incubated at 37°C and fluorescence was recorded (exc 360 nm, em 435 nm). Results are expressed as the fold-activation relative to the control. Acknowledgments
Financial support of this work by the CNRS and the University Paris-Est (PhD grant) is gratefully acknowledged.
[2] [3]
H. M. R. Hoffmann, J. Rabe, Synthesis and Biological Activity of α-Methylene-γ-butyrolactones, Angew. Chem. Int. Ed. 24 (1985) 94-110. N. H. Fischer, T. Lu, C. L. Cantrell, J. Castaneda-Acosta, L. Quijano, S. Franzblau, Antomycobacterial Evaluation of Germacranolides, Phytochemistry 49 (1998) 559-564. T.-C. Wang, K.-H. Lee, Y.-L. Chen, S.-S. Liou, C.-C. Tzeng, Synthesis and Anticancer Evaluation of certain γ-aryloxymethyl-α-methylene-γ-phenyl-γ-butyrolactones, Bioorg. Med. Chem. Lett. 8 (1998) 2773-2776.
EP
[1]
TE D
References and notes
Y. Higuchi, F. Shimoma, M. Ando, Synthetic Method and Biological Activities of cis-Fused α-Methylene γLactones, J. Nat. Prod. 66 (2003) 810-817.
[5]
M. A. Hughes, J. M. McFadden, C. A. Townsend, New α-methylene-γ-butyrolactones with antimycobacterial properties, Bioorg. Med. Chem. Lett. 15 (2005) 3857–3859.
[6]
N. Petragnani, H. M. C. Ferraz, G. V. J. Silva, Advances in the Synthesis of α-Methylenelactones, Synthesis (1986) 157-183. M. Pohmakotr, W. Harnying, P. Tuchinda, V. Reutrakul, Vicinal Dianion of Triethyl Ethanetricarboxylate:
[7]
AC C
[4]
Syntheses of (±)-Lichesterinic Acid, (±)-Phaseolinic Acid, (±)-Nephromopsinic Acid, (±)-Rocellaric Acid and [8]
(±)-Dihydroprotolichesterinic Acid, Helv. Chim. Acta 85 (2002) 3792-3813. D. Blanc, J. Madec, F. Popowyck, T. Ayad, P. Phansavath, V. Ratovelomanana, J.-P. Genêt, General Enantioselective Synthesis of Butyrolactone Natural Products via Ruthenium-SYNPHOS-Catalyzed Hydrogenation Reactions, Adv. Synth. Catal. 349 (2007) 943-950.
[12] [13]
[14] [15] [16]
[17] [18] [19]
synthesis of diastereoisomeric ethyl γ-benzyl paraconates and determination of the absolute configuration of their acids, Tetrahedron: Asymmetry 17 (2006) 2344–2353. A. M. Jacobine, W. Lin, B. Walls, C. K. Zercher, Formation of γ-Lactones through CAN-Mediated Oxidative Cleavage of Hemiketals, J. Org. Chem. 73 (2008) 7409-7412. Y. Li, Z.-A. Zhao, H. He, S.-L. You, Stereoselective Synthesis of γ-Butyrolactones via Organocatalytic Annulations of Enals and Keto Esters Adv. Synth. Catal. 350 (2008) 1885–1890. S. N. Greszler, J. S. Johnson, Diastereoselective Synthesis of Pentasubstituted γ-Butyrolactones from Silyl Glyoxylates and Ketones through a Double Reformatsky Reaction Angew. Chem. Int. Ed. 48 (2009) 3689– 3691. T. Shono, H. Hamaguchi, I. Nishiguchi, M. Sasaki, T. Miyamoto, M. Miyamoto, S. Fujita, New Zinc Promoted
TE D
[20]
RI PT
[11]
SC
[10]
S. Bazin, L. Feray, N. Vanthuyne, D. Siri, M. P. Bertrand, α-β-Unsaturated diesters: radical acceptors in ACCEPTED MANUSCRIPT dialkylzinc-mediated tandem radical addition/aldol condensation. A straightforward synthesis of racnephrosteranic acid, Tetrahedron 63 (2007) 77-85. H.-C. Kim, O.-S. Park, Efficient stereoselective synthesis of enantiopure 2-substituted paraconic acids, Tetrahedron: Asymmetry 19 (2008) 896–899. M. Amador, X. Ariza, J. Garcia, J. Ortiz, A Straightforward Synthesis of (-)-Phaseolinic Acid, J. Org. Chem 69 (2004) 8172-8175. For a recent review on the synthesis of paraconic acids, see: R. Bandichhor, B. Nosse, O. Reiser, Paraconic Acid-The Natural products from Lychen Symbiont, O. Top. Curr. Chem. 243 (2005) 43-72. M. M. Murta, M. B. M. De Azevedo, A. E. Greene, Synthesis and Absolute Stereochemistry of (-)Protolichesterinic Acid, Antitumor Antibiotic Lactone from Cetraria Islandica, J. Org. Chem. 58 (1993) 75377541. C. Böhm, O. Reiser, Enantioselective Synthesis of (-)-Roccellaric Acid, Org. Lett. 3 (2001) 1315-1318. K. Müller, Pharmaceutically relevant metabolites from lichens, Appl. Microbiol. Biotechnol. 56 (2001) 9-16. F. Berti, F. Felluga, C. Forzato, G. Furlan, P. Nitti, G. Pitacco, E. Valentin, M. T. Barros, Chemoenzymatic
M AN U
[9]
Synthetic Reaction of γ-Butyrolactones Derivatives, Chem. Lett. (1981) 1217-1220. [21] F. D’Onofrio, R. Margarita, L. Parlanti, G. Piancatelli, M. Sbraga, Tandem Michael-aldol induced ring closure of dimethyl-2-phenylselenofumarate: a diastereoselective entry to novel 4-phenylselenobutano-4-lactone derivatives, versatile precursors of naturally occurring compounds, Chem. Commun. (1998) 185-186.
EP
[22] A. Méou, L. Lamarque, P. Brun, Efficient MnIII-mediated synthesis of functionalized trans-3,4-disubstituted γbutyrolactones, Tetrahedron Lett. (43) 2002 5301-5304.
AC C
[23] The synthesis of monosubstituted lactones (N-Carbamoylmethyl-α-aminobutyrolactones) by the Ugi multicomponent reaction has been reported, see: S. J. Park, G. Keum, S. B. Kang, H. Y. Koh, Y. Kim, A facile synthesis of N-carbamoylmethyl- α -aminobutyrolactones by the Ugi multicomponent condensation reaction, Tetrahedron Lett. 39 (1998) 7109-7112. [24] For the synthesis of α-methylene-γ-butyrolactones starting from preformed alkylcopper reagents, Michael
[25] [26] [27] [28]
acceptors and aldehydes, see: A. Sidduri P. Knochel, New preparation of α-methylene-γ-butyrolactones mediated by (iodomethyl)zinc iodide, J. Am. Chem. Soc. 114 (1992) 7579–7581. J. Zhu, H. Bienaymé, Multicomponent Reactions, Wiley-VCH, Weinheim, 2005. R. V. A. Orru, M. De Greef, Recent Advances in Solution-Phase Multicomponent Methodology for the Synthesis of Heterocyclic Compounds, Synthesis (2003) 1471-1499. J. Zhu, Recent Developments in the Isonitrile-Based Multicomponent Synthesis of Heterocycles, Eur. J. Org. Chem. (2003) 1133-1144. C. Simon, T. Constantieux, J. Rodriguez, Utilisation of 1,3-Dicarbonyl Derivatives in Multicomponent Reactions, Eur. J. Org. Chem. (2004) 4957-4980.
[29] A. Dömling, Recent Developments in IsocyanideMANUSCRIPT Based Multicomponent Reactions in Applied Chemistry, ACCEPTED Chem. Rev. 106 (2006) 17-89. [30] D. M. D’Souza, T. J. J. Müller, Multi-component syntheses of heterocycles by transition-metal catalysis, Chem. Soc. Rev. 36 (2007) 1095-1108. [31] G. Guillena, D. J. Ramón, M. Yus, Organocatalytic enantioselective multicomponent reactions (OEMCRs), Tetrahedron: Asymmetry 18 (2007) 693-700.
RI PT
[32] The synthesis of monosubstituted lactones (N-Carbamoylmethyl-α-aminobutyrolactones) by the Ugi multicomponent reaction has been reported, see: S. J. Park, G. Keum, S. B. Kang, H. Y. Koh, Y. Kim, A facile synthesis of N-carbamoylmethyl- α -aminobutyrolactones by the Ugi multicomponent condensation reaction, Tetrahedron Lett. 39 (1998) 7109-7112. [33] For the synthesis of α-methylene-γ-butyrolactones starting from preformed alkylcopper reagents, Michael acceptors and aldehydes, see: A. Sidduri P. Knochel, New preparation of α-methylene-γ-butyrolactones mediated by (iodomethyl)zinc iodide, J. Am. Chem. Soc. 114 (1992) 7579–7581.
[41] [42]
[43]
[44]
TE D
[40]
EP
[38] [39]
Approach to Novel 2,3-Di and 2,2,3-Trisubstituted-3-methoxycarbonyl-γ-Butyrolactones, Eur. J. Org. Chem. (2010) 5279-5286. H. Fillon, C. Gosmini, J. Périchon, New Chemical Synthesis of Functionalized Arylzinc Compounds from Aromatic or Thienyl Bromides under Mild Conditions Using a Simple Cobalt Catalyst and Zinc Dust, J. Am. Chem. Soc. 125 (2003) 3867-3870. Reactions were monitored by Gas Chromatography using an internal standard. R.W. Wang, L.I. Rebhum, S.M. Kupcham. Antimitotic and antitubulin activity of the tumor inhibitor staganacin. Cancer Res. 37 (1977) 3071-3079. For some representative reviews on combretastatins and analogues, see: (a) A. Cirla, J. Mann, Combretastatins: from natural products to drug discovery, Nat. Prod. Rep. 20 (2003) 558–564; (b) H. P. Hsieh, J. P. Liou, N. Mahindroo, Pharmaceutical design of antimitotic agents based on combretastatins, Curr. Pharm. Des. 11 (2005) 1655-1677. X. Liu, H. Zou, C. Slaughter, X. Wang. DFF, a Heterodimeric Protein That Functions Downstream of Caspase3 to Trigger DNA Fragmentation during Apoptosis. Cell 89 (1997) 175-184. G. Loor, J. Kondapalli, J.M. Schriewer, N.S. Chandel, T.L. Vanden Hoek, P.T. Schumacker. Menadione triggers cell death through ROS-dependent mechanisms involving PARP activation without requiring apoptosis. Free Radic. Biol. Med. 49 (2010) 1925-1936. DW. Nicholson, A. Ali, N.A. Thornberry, J.P. Vaillancourt, C.K. Ding, M. Gallant, Y. Gareau, P.R. Griffin, M. Labelle, Y.A. Lazebnik, N.A. Munday, S.M. Raju, M.E. Smulson, T.T. Yamin, V.L. Yu, D.K. Miller. Identification and inhibition of the ICE/CED-3 protease necessary for mammalian apoptosis. Nature 376 (1995) 37-43. L. Eloy, A.S. Jarrousse, M.L. Teyssot, A. Gautier, L. Morel, C. Jolivalt, T. Cresteil, S. Roland. Anticancer Activity of Silver(I)–N-Heterocyclic Carbenes: Caspase-independent Induction of Apoptosis via the Mitochondrial Apoptosis Inducing Factor (AIF), ChemMedChem 7 (2012) 805-814.
AC C
[37]
M AN U
SC
[34] E. Le Gall, C. Haurena, S. Sengmany, T. Martens, M. Troupel, Three-Component Synthesis of α-Branched Amines under Barbier-like conditions, J. Org. Chem. 74 (2009) 7970-7973. [35] C. Le Floch, E. Le Gall, E. Léonel, T. Martens, T. Cresteil, Synthesis and cytotoxic evaluation of novel paraconic acid analogs, Bioorg. Med. Chem. Lett. 21 (2011) 7054-7058. [36] C. Le Floch, E. Le Gall, E. Léonel, J. Koubaa, T. Martens, P. Retailleau, A Cobalt-Catalyzed Multicomponent
S0223-5234(14)01002-2
DOI:
10.1016/j.ejmech.2014.10.074
Reference:
EJMECH 7482
To appear in:
European Journal of Medicinal Chemistry
Received Date: 17 February 2014 Revised Date:
23 October 2014
Accepted Date: 26 October 2014
Please cite this article as: C. Le Floch, E. Le Gall, S. Sengmany, P. Renevret, E. Léonel, T. Martens, T. Cresteil, Synthesis of 2,3-di- and 2,2,3-trisubstituted-3-methoxycarbonyl-γ-butyrolactones as potent antitumor agents, European Journal of Medicinal Chemistry (2014), doi: 10.1016/j.ejmech.2014.10.074. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Multicomponent synthesis of densely substituted paraconic acid analogs In vitro cytotoxicity evaluation of the compounds in human cancer cell lines Sub-micromolar activity of one of the tested compounds Determination of the mode of action using flow cytometry
AC C
EP
TE D
M AN U
SC
RI PT
Activation of the apoptotic cascade without prominent blockade of the cell cycle
ACCEPTED MANUSCRIPT
AC C
EP
TE D
M AN U
SC
RI PT
Graphical Abstract
ACCEPTED MANUSCRIPT
Synthesis of 2,3-di- and 2,2,3-trisubstituted-3-methoxycarbonyl-γγ-butyrolactones as potent antitumor agents Camille Le Flocha, Erwan Le Galla,*, Stéphane Sengmanya, Patrice Renevretb, Eric Léonela, Thierry Martens,a Thierry Cresteilc a
RI PT
Électrochimie et Synthèse Organique, Institut de Chimie et des Matériaux Paris-Est, UMR 7182 CNRS - Université Paris-Est Créteil, 2-8 rue Henri Dunant, 94320 Thiais, France b Plateforme Chromatographie Analytique et Préparative, Institut de Chimie et des Matériaux Paris-Est, UMR 7182 CNRS – Université Paris-Est Créteil,2-8 rue Henri Dunant, 94320 Thiais, France c Ciblothèque cellulaire, Institut de Chimie des Substances Naturelles, CNRS-UPR 2301, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France
SC
∗ Corresponding author. Tel.: +33-149781135; fax: +33-149781148; e-mail: [email protected]
Keywords: Lactones; Paraconic acid analogs; Multicomponent reaction; Biological evaluation; Cytotoxic activity.
M AN U
Abstract: Various 2,3-substituted γ-butyrolactones have been synthesized by three-component reaction of aryl bromides, dimethyl itaconate and carbonyl compounds. The in vitro cytotoxic activity of these products was evaluated against a representative panel of cancer cell lines (KB, HCT116, MCF7, MCF7R, PC3, SK-OV3, HL60 and HL60R). One compound (4x) displays a good anti-proliferative activity with IC50 in the sub-micromolar range. The mechanism of action has been investigated using flow cytometry. 1. Introduction
TE D
The γ-butyrolactone core is widely present in natural compounds possessing biological activities [1-6]. In this context, paraconic acids [7-12] (γ-butyrolactones bearing a carboxylic acid function at the position β to the carbonyl,
EP
see scheme 1), constitute an important group of γ-butyrolactones that not solely display antitumor and antibiotic activities, but also represent relevant building blocks for the synthesis of diverse pharmacologically active compounds [13-15]. Due to these attractive properties, their synthesis has been the subject of tremendous efforts in the past few years. However, although the preparation of these compounds has been described through several strategies [16-24], the straightforward synthesis of densely substituted γ-butyrolactones still represents a challenge, especially for structure-activity relationship (SAR) studies.
AC C
In this context, multicomponent reactions (MCRs) [25-33] are processes of high interest as they potentially provide structural complexity starting from simple and/or commercial reagents, thus enabling a straightforward access to molecular diversity. In recent papers, we highlighted the use of aryl halides as precursors of organometallic species, in multicomponent reactions [34]. Given the high functional tolerance displayed by these species, it was envisaged their utilization in multicomponent reactions providing diversely-substituted products and the further biological assessment of the newly constituted libraries of compounds. Therefore, we report herein the preparation of densely substituted paraconic acid analogues by a zinc-mediated, cobalt-catalyzed multicomponent reaction between aryl halides, carbonyl compounds and dimethyl itaconate and their evaluation as potent antitumor agents.
ACCEPTED MANUSCRIPT
2. Results and discussion 2.1. Chemistry
M AN U
SC
RI PT
The synthesis of densely-substituted paraconic acid analogs 4 was envisaged via a reductive three component coupling between a carbonyl compound 1, an aryl bromide 2 and dimethyl itaconate 3 (scheme 1) [35-36]. The reaction was anticipated to proceed via a conjugate addition/aldol reaction/cyclization domino reaction, whose initiation would be performed by the initial in situ generation of an arylmetal reagent (that would undergo the key conjugate addition onto itaconate, starting point of the cascade).
Scheme 1. Some natural paraconic acids and retrosynthetic approach to synthetic analogs The initial metallation of the aromatic bromide 2 was considered through the use of the Zn(0)/Co(II) system [37], which had already provided reliable results in multicomponent processes. Preliminary experiments revealed that the most convenient experimental conditions were the following: acetonitrile is used as a solvent, zinc dust as a reductive metal, CoBr2 as a catalyst and the aryl bromide, the aldehyde and dimethyl itaconate are stirred at 60°C for a few
TE D
hours [38]. These conditions allowed the synthesis of a representative set of diversely-substituted γ-butyrolactones. Results are reported in Table 1.
AC C
EP
Table 1. Synthesis of γ-butyrolactones 3.a
Entry
Carbonyl compound 1
Aryl bromide 2
Yield (%)b
Product
4a
64
2
4b
99
3
4c
54
4
4d
48
1
ACCEPTED MANUSCRIPT 4e
55c
6
4f
95
7
4g
44
8
O
Br
9
4h
71c
4i
33
SC
O
RI PT
5
4j
56
4k
98
4l
67
4m
78
4n
56
4o
96
16
4p
78
17
4q
73
18
4r
98c
M AN U
10
11
14
AC C
15
EP
13
TE D
12
ACCEPTED MANUSCRIPT O
Br
4s
42
20
4t
56
21
4u
49
19
RI PT
O
22
27
4w
82
SC
23
4v
4x
85
4y
60
4z
87c
4aa
54
4ab
52
4ac
41
30
4ad
22
31
4ae
23
32
4af
15c
33
4ag
46
M AN U
24
25
28
AC C
29
EP
27
TE D
26
ACCEPTED MANUSCRIPT 34
4ah
99
35
4ai
89
4aj
51
O O H3C
36
4ak
52
4al
66
SC
CO2Me
RI PT
F3C
14
37
38
4am
M AN U
39 a
Experiments were conducted with 20 mL of acetonitrile, 10 mmol of the carbonyl compound 1, 15 mmol of the aryl bromide 2, 7.9 g (50 mmol) of dimethyl itaconate 3, 3 g (46 mmol) of zinc dust, 0.44 g (2 mmol) of CoBr2, at 60°C for 1-3 h. b Isolated yield. c Reaction conducted at room temperature.
These results reveal that an important variety of functionalized aromatic aldehydes and halides is useable in the
TE D
process. Ketones also undergo the reaction to furnish 2,2,3,3-tetrasubstituted γ-butyrolactones (Table 1, entries 2339). It can be noted that cyclic ketones can also be employed in the process to give rise to the formation of spiranic compounds, albeit in far more limited yields (Table 1, entry 39). Under these general conditions, mixtures of diastereoisomers were obtained (in the form of racemic mixtures of enantiomers). Diastereoisomeric ratios were typically ranging from 80:20 to 60:40. Due to difficulties encountered in the separation of the diastereoisomers, the initial biological evaluation was carried out on well mastered mixtures (~ 50:50) of the diastereoisomers in order to both obtain reliable results and comparable scales of biological activities.
EP
2.2. Evaluation of the cytotoxic activities
AC C
The inhibition of cell proliferation/viability by these diversely functionalized molecules was evaluated in vitro against a panel of human cancer cell lines (KB (nasopharyngeal), HCT116 (colon), MCF7 (breast), and HL60 (leukemia)). Results are reported in Table 2. Table 2. Percentage of cell growth inhibition at 10 µM in DMSO. Entry
Compound
KB
HCT116
MCF7
1
4a
18±6
0±3
0±7
2
4b
12±2
0±10
0±13
3
4c
4±7
4±11
0±9
4
4d
39±8
14±2
5
4e
42±5
25±2
6
4f
19±11
7
4g
8
4h
9 10
HL60
Entry
Compound
KB
HCT116
MCF7
HL60
22±11
21
4u
32±4
0±5
0±6
29±8
19±2
22
4v
13±8
12±2
28±2
8±4
4±4
23
4w
6±5
9±5
13±9
22±1
11±5
34±4
24
4x
95±1
61±1
56±2
82±1
35±2
28±4
25
4y
5±7
14±5
16±3
30±1
4±3
0±4
15±7
26
4z
9±4
13±2
10±6
34±2
0±1
14±7
12±8
37±5
27
4aa
56±1
20±3
8±8
64±2
7±1
23±3
18±10
42±9
28
4ab
22±5
25±1
12±18
17±3
4i
0±17
18±4
11±5
18±6
29
4ac
11±5
28±3
21±7
30±4
4j
0±11
16±5
1±16
7±6
30
4ad
15±11
25±3
19±5
28±2
4ae 4±9 37±5 MANUSCRIPT 31 ACCEPTED
11
4k
33±2
12
4l
0±6
0±4
4±7
2±4
32
13
4m
25±8
10±1
15±4
14±4
33
14
4n
31±7
0±11
0±1
23±7
15
4o
2±5
7±2
17±2
27±1
16
4p
16 ± 12
24 ± 2
27 ± 6
17
4q
0±4
20±3
13±5
18
4r
6±7
19±3
12±9
19
4s
0±4
22±2
20
4t
0±16
13±5
21±7
22±4
20±4
21±2
4af
0±12
18±1
6±5
0±11
4ag
22±3
44±3
35±5
43±3
34
4ah
0±16
0±18
2±16
7±11
35
4ai
0±13
8±3
7±4
24±3
32 ± 1
36
4aj
34±1
14±3
14±3
20±1
10±6
37
4ak
38±5
30±6
46±3
52±1
22±3
38
4al
0±7
15±3
7±4
9±4
8±9
10±2
39
4am
7±13
0±3
1±10
4±2
3±11
0±6
RI PT
0±5
M AN U
SC
It can be noted that most molecules exhibit a low to moderate antiproliferative activity on both KB and HL60 cancer cell lines. With a bare phenyl at the 2 position (Table 2, entries 1-10), the presence of a CF3 group on the benzyl moiety provides increased activities, especially at the meta and ortho position (Table 2, entries 4-5). Although a 4-methoxybenzyl group at the 3 carbon does not result in increased activities (Table 2, entry 6) when a bare phenyl is present at the 2 carbon, it can be noted that some substantial enhancement of the cytotoxicity is observed when the phenyl group is substituted by a F or a CF3 (Table 2, entries 11 and 14). With a 2 carbon substituted by both a phenyl and a methyl group (Table 2, entries 23-26 and 30-37), a methoxy group located at the para position of the benzyl moiety provides the best results (Table 2, entry 27). Indeed, compound 4x, obtained from acetophenone, 4bromoanisole and dimethyl itaconate, exhibits an increased antiproliferative activity compared to the other products,
AC C
EP
TE D
with cellular growth inhibitions higher than 50% in the four cell lines at a concentration of 10 µM. The replacement of the CH3 group of 4x by a CF3 (Table 2, entry 27) or by a CH2CH3 (Table 2, entry 29) results in a moderate to important decrease of the cytotoxicity. The cytotoxicity also drops when the 4-methoxybenzyl group is replaced by a benzyl (Table 2, entry 28), indicating the crucial importance of the OMe substituent. Moreover, although a CF3 group on the benzyl group had provided increased activities when the 2 carbon was trisubstituted (Table 2, entries 4-5), no significant modification of the cytotoxicity is observed when the 2 carbon is quaternary (comparison of entry 23 and entries 30-32 of Table 2). It can also be noted that contrary to what is observed with some well known antitumor agents like steganacin [39] or combretastatin A-4 [40], which acts by initial binding to tubulin, polymethoxylated phenyl groups do not bring a notable improvement of biological activity, both with a trisubstituted (Table 2, entries 15-20) and a tetrasubstituted 2 carbon (Table 2, entries 34-35). The activity of the lead 4x seems to be linked to the presence of both Me and Ph at the 2 position. Indeed, the functionnalization of the phenyl by a CF3 group (Table 2, entry 37) also results in a slight decrease of the biological activity compared to a bare phenyl. Although the cytotoxicities are far more limited than with acetophenone as one of the starting compounds, it can be noted that aliphatic aldehydes can be used in the process to introduce an aliphatic side chain. This latter seems to promote a slight increasing of the cytotoxicity against MCF7 (Table 2, entry 22). On the contrary, compound 4al, exhibiting two Me groups at the 2 position and the more unusual spiranic compound 4am, obtained from a cyclic ketone, are characterized by a general lack of activity (Table 2, entries 38-39). A deeper investigation of the anti-proliferative activities of compound 4x was undergone. Therefore, the determination of the IC50 values was undertaken on KB (figure 1), HCT116 (data not shown), MCF7 (data not shown) and HL60 (data not shown) cancer cell lines. These experiments were carried out in duplicate. The minimum and maximum values of IC50 are indicated in Table 3.
Figure 1. Graphical determination of IC50 values. ACCEPTED
MANUSCRIPT
50
0.001
0.01
0.1
1
10
Concentration (µM)
Table 3. IC50 of compound 4x.
100
HCT116
MCF7
HL60
0.4 / 0.9
1.3 / 2.4
2.8 / 6.4
0.9 / 2.0
SC
KB
M AN U
IC50 min / max (µM)
RI PT
0
Cell growth inhibition (%)
100
Graph#1
As it can be observed from these results, IC50 values are very homogeneous and comprised in the 0.1-1 µM range. These promising results prompted us to undertake an extended evaluation of the cytotoxic activities of compound 4x. Therefore, this latter was assessed against an additional panel of cancer cell lines including, among others, multidrug resistant cell lines MCF7R and HL60R. Overall results are reported in Table 4. Table 4. Cellular growth inhibition percentage of compound 4x at 10 µM in DMSO. HCT116
95 ± 1
61 ± 1
MCF7
MCF7R
TE D
KB
56 ± 2
82 ± 1
HL60
HL60R
PC3
SK-OV3
82 ± 1
92 ± 2
68 ± 1
76 ± 1
These results confirm the potent in vitro activities of compound 4x against various cancer cell lines. The inhibition
AC C
EP
of the proliferation of PC3 (prostate) and SK-OV3 (ovary) cancer cell lines is significant at 10 µM with respective 68% and 76% inhibition of cellular growth. In addition, these results might indicate that compound 4x is not substrate of P-gp, since multidrug resistant cell lines MCF7R and HL60R are affected in the same fashion as their sensitive counterpart cell lines. 2.3. Mechanism of action
Apoptosis and necrosis are two distinct and redundant forms of cell death that can occur in response to chemical aggression. These two cellular processes feature different and complementary modes of action: apoptosis or programmed cell death is executed in animal cells via the activation of cellular proteases leading to the cleavage of chromatin into nucleosomal fragments [41], while necrosis involves the destruction of the plasma membrane leading to the release of cytosolic lactic dehydrogenase into the culture medium, used as the hallmark of necrosis. Among chemicals capable to promote necrosis, high doses of menadione generate high levels of intracellular reactive oxidant species inducing lethal oxidant stress [42]. At first, we evaluated the effect of compound 4x on the necrotic process.
Figure 2. Total LDH activity in HL60 cells (panel A) and in the supernatant of intact cells (panel B) treated for 48 h with ACCEPTED MANUSCRIPT reference compounds and compound 4x. Control cells received DMSO only (1% final volume) and positive control 50 µM menadione or 1 µM doxorubicin. Results are expressed as the percentage±SE of LDH activity presented in untreated cells.
B
SC
RI PT
A
M AN U
As displayed in figure 2A, after the complete lysis of cells with triton X100, the total LDH activity reflecting the total cell number was reduced and confirmed the antiproliferative activity of compound 4x. In intact cells treated with the reference compound doxorubicin and compound 4x (figure 2B), the membrane integrity was maintained and no release of cytosolic LDH was noticed, whereas 50 µM menadione produced as expected a marked release of LDH into the culture medium. This clearly indicated that compound 4x is not necrotic for cells.
EP
TE D
Cell death mechanism was next evaluated by FACS using two impermeant dies for intact cells, annexin and 7 AAD. The first event occurring during apoptosis is the externalization of phosphatidyl-choline from the inner membrane leaflet to the outer plasma membrane, followed by the secondary loss of membrane integrity during late apoptosis/necrosis. In intact cells, phosphatidyl-choline is inaccessible to annexin, as well as the DNA intercalator 7AAD cannot penetrate the nucleus. During early apoptosis, phosphatidyl-choline is externalized and becomes accessible to annexin whereas cells remained impermeable to 7-AAD. In late apoptosis the cell membrane integrity is lost allowing both annexin and 7-AAD to freely penetrate into the cell and tag their respective targets. Therefore, the effect of a 48 h exposure to the reference compound doxorubicin and to increasing doses of compound 4x was explored in HL60 cells. Doxorubicin elicited a massive entry of cells in the early apoptotic stage, as well as compound 4x did in a dose-dependent manner (Table 5). Therefore we can conclude that compound 4x primarily induces cell death through the activation of apoptosis.
AC C
Table 5. FACS analysis of apoptosis in HL60 cells treated for 48 h with compound 4x. Control cells received dmso only (1% final volume) and positive control 100 nM doxorubicin. Results are expressed as the percentage of cells in the different stages of apoptosis.
dmso
Dead cells %
Late apoptosis %
Intact cells %
Early apoptosis %
0.4
0.4
80.7
18.5
3.15
14.7
81.65
2 µM 0.35
0.65
61.45
37.65
5 µM 0.9
2.2
50.55
46.4
10 µM 1.65
4.25
40.7
53.35
doxo 100 nM 0.5 4x
It is assumed that caspase 3 is the terminal effector of the apoptotic cascade [43]: this protease is activated in cell undergoing apoptosis after processing of the inactive procaspase 3 into its catalytically active form, capable to cleave DEVD-AMC and release the fluorescent moiety. Therefore, HL60 cells were treated with compound 4x for 24 and 48 h and with the positive reference 100 nM doxorubicin. Activation of caspase 3 activity was enhanced as early as
24 h of treatment (data not shown) and ACCEPTED was maximal after 48 h (Figure 3) with a 4x concentration of 5 µM. So we MANUSCRIPT can conclude that compound 4x induced apoptosis in cells through the activation of the caspase cascade. Figure 3. Activation of caspase 3 in HL60 cells treated for 48 h with compound 4x and the positive control 100 nM doxorubicin. Results are expressed as the percentage±SE of caspase 3 activity presented in cells treated with dmso only. 800% 700% 600%
400% 300% 200% 100%
SC
4x 5µM
4x 2µM
4x 1µM
M AN U
Doxo
dmso
0%
4x 10µM
RI PT
500%
EP
TE D
In the last part of this study, the effect of compound 4x was tested on the cell cycle. Four phases are classically defined in mammalian cell cycle: in resting cells (G0/G1) 2n chromosomes are present, followed by DNA synthesis (S) to reach 4n chromosomes (G2) before mitosis and cell division (M). Some chemicals are known to stop the cell cycle at a specific step according to their target and mode of action. Therefore it is possible to get insight in the mode of action of anti-proliferative compound by an accurate determination of cell proportion in each cycle phase. Cells were treated with the positive reference or with increasing concentrations of compound 4x before the addition of a DNA marker. As shown in figure 4, the reference compound doxorubicin elicited a blockade of the cell cycle in phase G2/M. Compound 4x at a low concentration had the same albeit moderate and transient effect, together with a slight increase of the number of cells in an apoptotic situation (sub G1). The number of apoptotic cells increased in a dose-dependent manner with compound 4x, without prior augmentation of cells in G2/M. Therefore it is possible to conclude that 4x did not elicit a massive arrest of cell proliferation in a specific stage but actively promoted apoptosis.
AC C
Figure 4. Cell cycle analysis of HL60 cells treated with doxorubicin and compound 4x for 48 h. Results are the percentage of cells in the different cycle stages after staining with propidium iodide and FACS analysis.
DMSO
doxo 50 nM
4x 2 µM
4x 5 µM
4x 10 µM
23.0 36.3 23.4 ACCEPTED MANUSCRIPT
G0/G1
42.9
19.5
S Phase
45.0
32.5
24.0
25.6
29.7
G2/M
11.6
40.0
25.6
12.2
13.1
SubG1
0.5
4.5
14.1
38.9
37.7
RI PT
Finally, as biological activities are generally linked to stereochemical pattern, we envisaged to further assess the cytotoxicity of both diastereoisomers of the lead compound 4x, taken independently. Therefore, a delicate chromatographic separation of a reaction mixture of 4x was undergone and fortunately, we succeeded in the isolation of both diastereoisomers 4xA and 4xB, which were submitted to a cytotoxic evaluation on KB, HCT116, MCF7 and HL60 cells. Results are indicated in Table 6.
SC
Table 6. In vitro cytotoxicity profile of diastereoisomers 4xA and 4xB.a
Percentage of cell growth inhibition at 10 µM in DMSO
4xA
15±5
4xB
98±1
a
HCT116
MCF7
M AN U
KB
HL60
0±19
0±10
24±2
56±2
59±3
68±1
The stereochemistry of both diastereoisomers 4xA and 4xB had been obtained previously through X-Ray diffraction experiments, see ref. 36 for details.
3. Conclusion
TE D
As diastereoisomer 4xA does not possess significant biological activity compared to 4xB, which is far more active, these results clearly indicate that the activity of the ~50:50 mixture (so-called compound 4x, see Table 2, entry 24) is mostly due to the trans diastereoisomer 4xB.
AC C
EP
In summary, the multicomponent reaction reported herein provides a reliable access to a wide variety of diversely substituted paraconic acid analogs. The biological activity of this novel class of compounds was evaluated against a representative set of human cancer cell lines. One of the molecules proved to exhibit a promising inhibition of cellular growth with IC50 values generally below 10-5 M. Its mode of action strongly suggested an activation of the apoptotic cascade without prominent blockade of the cell cycle. 4. Experimental 4.1. General
All reactions were carried out under argon atmosphere. Reagents and solvents were obtained from commercial suppliers and used without further purification. Reactions were monitored by gas chromatography (GC) on a Varian 3300 chromatograph fitted with a DB1 capillary column (l = 5 m, Ø = 0.32 mm, df = 0.4 µm). Melting points (mp) were determined on a Büchi Melting Point B-545. Infrared spectra were recorded on a Bruker TENSOR 27 spectrometer and treated via OPUS software. NMR spectra were recorded in CDCl3 at 400 MHz (1H), 100 MHz (13C), and 376 MHz (19F) on a Bruker Avance II 400 spectrometer. Chemical shifts (δ) are reported in parts per million (ppm) relative to the residual solvent signal. Coupling constant values (J) are given in Hertz (Hz) and refer to apparent multiplicities, indicated as follows: s (singlet); d (doublet); t (triplet); q (quadruplet); m (multiplet); dd (doublet of doublets). NMR peak assignments were determined using a combination of DEPT, HMBC, HSQC,
COSY and NOESY experiments. FlashACCEPTED chromatographyMANUSCRIPT was performed on silica gel (Merck, 35-70 µm particles, + 550 mesh). Mass spectra were recorded in ESI mode on a Thermo Scientific ITQ 700 GC-MS spectrometer fitted with a CPSIL5CB/MS capillary column (l = 25 m, Ø = 0.25 mm, df = 0.12 µm). Elemental analyses were carried out by the microanalysis facility, ICSN Gif-sur-Yvette, France. High resolution mass spectra were obtained from the Mass Spectroscopy facility of the Institut de Chimie Organique et Analytique, Orléans, France. Biological assays were carried out by the Ciblothèque Cellulaire facility of the IMAGIF platform, ICSN Gif-sur-Yvette, France. 4.2. General procedure for the synthesis of γ-butyrolactones 4a-am
M AN U
4.3. Separation of diastereoisomers 4xA and 4xB
SC
RI PT
A dried 100 mL round bottom flask was flushed with argon and charged with acetonitrile (20 mL). Dodecane (0.2 mL), zinc dust (3 g, 46 mmol), a carbonyl compound 1 (10 mmol), an aryl bromide 2 (15 mmol), and dimethyl itaconate 3 (7.9 g, 50 mmol) were added under stirring. Cobalt bromide (0.44 g, 2 mmol), trifluoroacetic acid (0.1 mL) and 1,2-dibromoethane (0.2 mL) were added successively to the mixture which was heated at 60°C until complete consumption of the aryl bromide (45 min. to 3 h, monitored by gas chromatography). The reaction mixture was then filtered through celite. Celite was washed several times with diethyl ether and the combined organic fractions were concentrated in vacuo. The crude reaction product was purified via flash column chromatography over silica gel using a pentane/diethyl ether (1:0 to 0:1) as an eluant to afford the five-membered ring lactone 4 as a mixture of diastereoisomers (50:50 to 70:30 typically).
AC C
EP
TE D
Diastereoisomers of compound 4x were separated using consecutive chromatographies using flash cartridges of opposite polarities. Diastereoisomer 4xB was obtained using a polar Merck EVFD24 Si60 15-40µm phase and a petroleum ether/ethyle acetate 100:0 to 85:15 gradient whereas 4xA was obtained from the remaining mixture of 4xA and 4xB using an apolar C18 Grace reversed-phase and a MeOH/H2O 50:50 to 80:20 gradient.
ACCEPTED MANUSCRIPT 4.4. Compounds characterization Methyl 3-benzyl-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4a Prepared following general procedure, using benzaldehyde (1.0 mL, 10 mmol, 1 eq.) and bromobenzene (1.6 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4aA and 4aB were obtained in a 76 : 24 ratio as a colorless H oil; yield: 1.99 g (64 %); Rf: 0.10 (pentane/diethyl ether mixture (7:3)); 1H NMR (CDCl3): δ = 2.19 (1HA, d, CO2Me J 13.7), 2.70 (1HB, d, J 17.5), 2.72 (1HA, d, J 17.6), 2.87 (1HA, d, J 13.7), 3.01 (1HB, d, J 13.8), 3.09 (1HB, d, J 17.5), 3.13 (1HA, d, J 17.6), 3.33 (3HA, s), 3.63 (1HB, d, J 13.8), 3.77 (3HB, s), 5.44 (1HA, s), 5.75 (1HB, s), 6.95 (2HA, dd, J 2.3, 7.8), 7.15 (2HB, dd, J 1.8, 8.1), 7.22 (2HA, d, J 7.8), 7.30 (2HB, d, J 8.1), 7.28-7.45 (12HA+B, m); 13C NMR (CDCl3): δ = 35.6 (1CA), 35.8 (1CB), 39.0 (1CA), 40.8 (1CB), 52.1 (1CB), 52.9 (1CA), 56.3 (1CA), 58.1 (1CB), 85.7 (1CA), 87.0 (1CB), 125.9 (1CA), 126.5 (1CB), 127.3-129.9 (20CA+B), 134.3 (1CB), 134.9 (1CA), 135.5 (1CA), 135.7 (1CB), 170.9 (1CB), 173.0 (1CA), 174.5 (1CA), 174.6 (1CB); IR: ν = 701, 747, 1011, 1165, 1200, 1733, 1785, 2953 cm-1; MS (EI): m/z = 233 (5), 219 (23), 218 (8), 205 (12), 204 (100), 203 (14), 191 (8), 187 (5), 186 (5), 176 (42), 172 (27), 145 (9), 144 (12), 134 (9), 117 (20), 116 (27), 115 (25), 91 (12); Anal. calcd. for C19H18O4 (310.12): C 73.53, H 5.85; found: C 73.21, H 5.71. O
RI PT
O
Methyl 3-(4-methoxycarbonylbenzyl)-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4b
Prepared following general procedure, using benzaldehyde (1.0 mL, 10 mmol, 1 eq.) and methyl-4bromobenzoate (3.22 g, 15 mmol, 1.5 eq.). Both diastereoisomers 4bA and 4bB were obtained in a 75 : H 25 ratio as a colorless oil; yield: 3.65 g, (99 %); Rf: 0.14 (pentane/diethyl ether mixture (7:3)); 1H NMR CO2 Me (CDCl3): δ = 2.12 (1HB, d, J 13.7), 2.57 (1HB, d, J 17.5), 2.58 (1HA, d, J 17.6), 2.79 (1HB, d, J 13.7), 2.90 (1HB, d, J 17.5), 2.92 (1HA, d, J 13.5), 3.01 (1HA, d, J 17.6), 3.20 (3HA, s), 3.56 (1HA, d, J 13.5), 3.65 (3HB, s), 3.76 (3HB, s), 3.77 (3HA, s), 5.32 (1HA, s), 5.64 (1HB, s), 6.92 (2HB, d, J 8.3), 7.11 (2HA, d, J 8.0), 7.14-7.33 (10HA+B, m), 7.57 (2HB, d, J 8.3), 7.84 (2HA, d, J 8.3); 13C NMR (CDCl3): δ = 35.6 (1CB), 36.0 (1CA), 38.9 (1CB), 40.7 (1CA), 52.1 (2CA), 53.0 (2CB), 56.0 (1CB), 58.1 (1CA), 85.6 (1CB), 87.2 (1CA), 125.9 (2CA+B), 125.7 (2CA), 126.4 (2CB), 128.4 (2CA), 128.6 (2CB), 129.0 (2CA+B), 129.3 (2CB), 129.5 (2CB), 129.7 (2CA), 129.8 (2CA), 134.1 (1CB), 134.6 (1CA), 140.1 (1CA), 140.9 (1CB), 166.7 (2CA+B), 170.6 (1CB), 172.7 (1CA), 174.2 (2CA+B); IR: ν = 702, 755, 1015, 1108, 1180, 1220, 1362, 1715, 1790, 2954 cm-1; MS (EI): m/z = 368 (4), 337 (15), 336 (5), 263 (22), 262 (100), 261 (5), 247 (7), 235 (15), 234 (91), 231 (7), 230 (21), 219 (28), 204 (5), 203 (22), 202 (18), 192 (33), 191 (6), 175 (28), 174 (26), 171 (9), 159 (7), 158 (6), 150 (22), 143 (22), 131 (6), 116 (6), 115 (17), 91 (13); Anal. calcd. for C21H20O6 (368.13): C 68.47, H 5.47; found: C 68.48, H 5.41. CO 2Me
SC
O
M AN U
O
Methyl 3-(4-(trifluoromethylbenzyl)-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4c CF3
AC C
EP
TE D
Prepared following general procedure, using benzaldehyde (1.0 mL, 10 mmol, 1 eq.) and 4bromobenzotrifluoride (2.10 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4cA and 4cB were obtained in a H 88 : 12 ratio as a colorless oil; yield: 2.03 g (54 %); Rf: 0.10 (pentane/diethyl ether mixture (7:3)) ; 1H CO2Me NMR (CDCl3): δ = 2.26 (1HB, d, J 13.8), 2.68 (1HB, d, J 17.6), 2.68 (1HA, d, J 17.2), 2.92 (1HB, d, J 13.8), 3.00 (1HA, d, J 13.6), 3.00 (1HA, d, J 17.2), 3.15 (1HB, d, J 17.6), 3.31 (3HA, s), 3.67 (1HA, d, J 13.6), 3.78 (3HB, s), 5.43 (1HA, s), 5.75 (1HB, s), 7.10 (2HB, d, J 8.1), 7.27 (2HA, d, J 8.2), 7.28-7.37 (10HA+B, m), 7.46 (2HB, d, J 8.1), 7.53 (2HA, d, J 8.2); 13C NMR (CDCl3): δ = 35.7 (1CB), 36.2 (1CA), 38.5 (1CB), 40.3 (1CA), 52.2 (1CA), 52.3 (1CB), 56.0 (1CB), 58.1 (1CA), 85.6 (1CB), 87.3 (1CA), 123.9 (2CA, q, J 272.0), 125.5 (4CA+B, q, J 3.7), 125.8 (2CA, q, J 273.4), 126.4 (2CB), 126.5 (2CA), 128.7 (2CB), 128.8 (2CA), 129.2 (1CB), 129.3 (1CA), 129.6 (1CA, q, J 33.0), 129.7 (1CB, q, J 33.1),130.0 (2CB), 130.2 (2CA), 134.0 (1CB), 134.6, (1CA), 139.9 (1CB), 140.0 (1CA), 170.6 (1CA), 172.6 (1CB), 174.0 (1CB), 174.2 (1CA); 19F NMR (CDCl3): δ = -62.6 (6FA+B); IR: ν = 701, 1016, 1114, 1164, 1324, 1712, 1791, 2361, 2955 cm-1; MS (EI): m/z = 273 (14), 272 (100), 245 (9), 244 (64), 240 (18), 219 (9), 213 (10), 212 (10), 202 (304), 185 (18), 184 (20), 175 (6), 165 (9), 115 (10); Anal. calcd. for C20H17F3O4 (378.11): C 63.49, H 4.53; found: C 63.25, H 4.66. O
O
Methyl 3-(3-(trifluoromethylbenzyl)-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4d Prepared following general procedure, using benzaldehyde (1.0 mL, 10 mmol, 1 eq.) and 3bromobenzotrifluoride (2.1 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4dA and 4dB were obtained in H a 35 : 65 ratio as a colorless solid, mp: 107°C; yield: 1.80 g (48 %); Rf: 0.25 (pentane/diethyl ether CO2Me mixture (7:3)); 1H NMR (CDCl3): δ = 2.29 (1HB, d, J 13.8), 2.72 (1HB, d, J 17.6), 2.74 (1HA, d, J 17.3), 2.93 (1HB, d, J 13.8), 3.03 (1HA, d, J 17.3), 3.04 (1HA, d, J 13.7), 3.15 (1HB, d, J 17.6), 3.33 (3HA, s), 3.69 (1HA, d, J 13.7), 3.79 (3HB, s), 5.47 (1HA, s), 5.80 (1HB, s), 7.19 (1HB, d, J 8.0), 7.24 (1HB, s), 7.30-7.39 (16HA+B, m); 13C NMR (CDCl3): δ = 35.5 (1CB), 36.4 (1CA), 40.2 (1CB), 41.1 (1CA), 52.1 (1CA), 52.9 (1CB), 56.1 (1CB), 58.3 (1CA), 85.5 (1CB), 87.3 (1CA), 123.8 (1CB, q, J 272.0), 123.9 (1CA, q, J 272.1), 124.1 (1CB, q, J 4.0), 124.3 (1CA, q, J 3.9), 125.6 (2CA), 126.2 (1CB, q, J 4.0), 126.5 (2CB), 126.6 (1CA, q, J 4.1), 128.6 (2CA), 128.8 (2CB), 129.1 (1CB), 129.2 (1CA), 129.3 (1CB), 129.4 (1CA), 130.8 (1CB, q, J 32.0), 130.9 (1CA, q, J 32.0), 133.1 (1CA), 133.3 (1CB), 134.2 (1CB), 134.6 (1CA), 136.8 (1CB), 136.9 (1CA), 170.6 (1CA), 172.7 (1CB), 174.2 (1CA + 1CB); 19F NMR (CDCl3): δ = -62.9 (6FA+B); IR: ν = 701, 757, 1014, 1120, 1162, 1330, 1452, 1732, 1789, 2953 cm-1; MS (EI): m/z = 234 (19), 232 (6), 204 (12), 203 (73), 201 (12), 200 (43), 192 (7), 175 (22), 174 (15), 173 (8), 172 (6), 145 (7), 132 (7), 131 (6), 129 (14), 128 (100), 117 (5), 116 (9), 115 (12), 105 (31), 100 (17), 99 (16), 91 (7), 85 (17), 77 (22), 51 (6); Anal. calcd. for C20H17F3O4 (378.11): C 63.49, H 4.53; found: C 63.33, H 4.31. O
O
CF3
ACCEPTED MANUSCRIPT
Methyl 3-(2-(trifluoromethylbenzyl)-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4e Prepared following general procedure, at room temperature, using benzaldehyde (1.0 mL, 10 mmol, 1 eq.) and 2-bromobenzotrifluoride (2.0 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4eA and 4eB were obtained H in a 35 : 65 ratio as a colorless oil; yield: 2.09 g (55 %); Rf: 0.32 (pentane/diethyl ether mixture (7:3)); 1H CF 3 CO2Me NMR (CDCl3): δ = 2.48 (1HA, d, J 17.6), 2.59 (1HB, d, J 17.8), 2.73 (1HB, d, J 15.8), 3.02 (1HB, d, J 15.8), 3.16 (1HA, d, J 17.5), 3.24 (1HB, d, J 17.8), 3.34 (3HA, s), 3.36 (1HA, d, J 15.7), 3.86 (3HB, s), 3.92 (1HA, d, J 15.7), 5.49 (1HA, s), 5.74 (1HB, s), 7.02 (1HB, d, J 7.8), 7.14 (1HA, d, J 7.8), 7.15-7.43 (14HA+B, m), 7.62 (1HB, d, J 7.8), 7.69 (1HA, d, J 7.8); 13C NMR (CDCl3): δ = 33.6 (1CB), 35.7 (1CB), 35.9 (1CA), 36.2 (1CA), 52.5 (1CA), 53.3 (1CB), 55.2 (1CB), 57.3 (1CA), 86.0 (1CB), 87.7 (1CA), 124.1 (2CA+B, q, J 272.0), 125.8 (1CB), 126.5 (1CA), 126.5 (2CA+B, q, J 10.0), 127.2 (1CB), 127.3 (1CA), 128.5 (2CA), 128.6 (2CB), 129.2 (2CB), 129.3 (2CA), 129.4 (1CA + 1CB, q, J 29.0), 129.5 (1CB), 129.6 (1CA), 132.0 (1CB), 132.3 (1CA), 134.0 (1CB), 134.6 (1CA), 135.0 (1CB), 135.1 (1CA), 171.6 (1CA), 173.7 (1CB), 174.1 (1CB), 174.2 (1CA); 19F NMR (CDCl3): δ = -57.2 (6FA+B); IR: ν = 771, 1014, 1116, 1161, 1217, 1312, 1440, 1632, 1712, 2956 cm-1; MS (EI): m/z = 273 (14), 272 (100), 252 (8), 244 (31), 240 (26), 225 (9), 224 (5), 219 (8), 213 (10), 212 (6), 209 (11), 207 (11), 204 (14), 202 (25), 193 (18), 185 (8), 173 (20), 165 (12), 164 (6), 159 (6), 115 (5); Anal. calcd. for C20H17F3O4 (378.11): C 63.49, H 4.53; found: C 63.29, H 4.61. O
RI PT
O
Methyl 3-(4-methoxybenzyl)-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4f
Prepared following general procedure, using benzaldehyde (1 mL, 10 mmol, 1 eq.) and 4-bromoanisole (1.8 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4fA and 4fB were obtained as a colorless oil; yield: H 3.24 g (95%); Rf: 0.14 (pentane/diethyl ether mixture (7:3)); Diastereoisomers could be separated from CO2 Me this mixture. Diastereoisomer 4fA: 1H NMR (CDCl3): δ = 2.70 (1HA, d, J 17.6), 2.92 (1HA, d, J 13.9), 3.07 (1HA, d, J 17.6), 3.33 (3HA, s), 3.57 (1HA, d, J 13.9), 3.79 (3HA, s), 5.43 (1HA, s), 6.84 (2HA, d, J 8.7), 7.07 (2HA, d, J 8.7), 7.28 (2HA, d, J 7.3), 7.38-7.40 (3HA, m); 13C NMR (CDCl3): δ = 35.7 (1CA), 40.1 (1CA), 52.1 (1CA), 55.3 (1CA), 58.3 (1CA), 87.1 (1CA), 114.0 (2CA), 125.2 (2CA), 127.4, (1CA), 128.5 (2CA), 129.1 (1CA), 131.0 (2CA), 134.9 (1CA), 158.9 (1CA), 170.9 (1CA), 174.6 (1CA); Diastereoisomer 4fB: 1H NMR (CDCl3): δ = 2.14 (1HB, d, J 13.9), 2.72 (1HB, d, J 17.7), 2.81 (1HB, d, J 13.9), 3.13 (1HB, d, J 17.7), 3.75 (3HB, s), 3.78 (3HB, s), 5.74 (1HB, s), 6.76 (2HB, d, J 8.7), 6.88 (2HB, d, J 8.7), 7.36 (2HB, d, J 7.1), 7.40-7.43 (3HB, m); 13C NMR (CDCl3): δ = 31.0 (1CB), 35.6 (1CB), 52.9 (1CB), 56.3 (1CB), 58.3 (1CB), 87.0 (1CB), 114.2 (2CB), 125.9 (2CB), 126.5 (1CB), 128.5 (2CB), 128.8 (1CB), 130.5 (2CB), 134.4 (1CB), 158.7 (1CB), 171.5 (1CB), 173.0 (1CB); IR: ν = 701, 728, 834, 1176, 1297, 1512, 1731, 1786, 2953 cm-1; MS (EI): m/z = 341 (9), 340 (43), 263 (5), 234 (16), 233 (6), 206 (28), 202 (6), 175 (8), 174 (8), 147 (14), 146 (21), 145 (7), 131 (5), 122 (12), 121 (100), 91 (7), 77 (7); Anal. calcd. for C20H20O5 (340.13): C 70.57, H 5.92; found: C 70.27 H 5.71. O
OMe
M AN U
SC
O
Methyl 3-(3-methoxybenzyl)-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4g OMe
AC C
EP
H
TE D
Prepared following general procedure, using benzaldehyde (1.0 mL, 10 mmol, 1 eq.) and 3bromoanisole (1.90 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4gA and 4gB were obtained in a 86 : 14 ratio as a colorless solid, mp: 52°C; yield: 1.51 g (44 %); Rf: 0.28 (pentane/diethyl ether mixture CO2Me (7:3)); 1H NMR (CDCl3): δ = 2.17 (1HA, d, J 13.7), 2.72 (1HB, d, J 17.6), 2.73 (1HA, d, J 17.7), 2.86 (1HA, d, J 13.7), 2.95 (1HB, d, J 13.7), 3.07 (1HB, d, J 17.6), 3.15 (1HA, d, J 17.7), 3.35 (3HB, s), 3.63 (1HB, d, J 13.7), 3.74 (3HA, s), 3.78 (3HB, s), 3.80 (3HA, s), 5.44 (1HB, s), 5.74 (1HA, s), 6.50 (1HA, d, J 2.0), 6.52 (1HA, d, J 7.9), 6.70 (1HB, d, J 2.0), 6.71 (1HB, d, J 7.9), 6.75 (1HA, dd, J 7.9, 2.0), 6.81 (1HB, dd, J 7.9, 2.0), 7.15 (1HA, t, J 7.9), 7.23 (1HB, t, J 7.9), 7.28-7.49 (10HA+B, m); 13C NMR (CDCl3): δ = 35.6 (1CA), 35.8 (1CB), 39.0 (1CA), 40.8 (1CB), 52.1 (1CB), 52.9 (1CA), 55.1 (2CA+B), 56.2 (1CA), 58.1 (1CB), 85.7 (1CA), 87.0 (1CB), 112.5 (1CA), 112.6 (1CB), 115.3 (1CA), 115.9 (1CB), 121.8 (1CA), 122.2 (1CB), 125.9 (2CB), 126.5 (2CA), 128.5 (2CB), 128.6 (2CA), 129.1 (1CA + 1CB), 129.2 (1CB), 129.6 (2CA), 129.8 (1CB), 134.3 (1CA), 134.9 (1CB), 137.2 (2CA+B), 173.0 (2CA+B), 174.5 (2CA+B); IR: ν = 699, 756, 1014, 1164, 1262, 1490, 1732, 1784, 2361, 2953 cm-1; MS (EI): m/z = 341 (10), 340 (48), 235 (6), 234 (30), 219 (14), 206 (16), 203 (6), 202 (15), 176 (8), 175 (53), 174 (38), 147 (22), 146 (39), 145 (7), 131 (8), 123 (9), 122 (100), 121 (7), 115 (10), 103 (7), 91 (16), 77 (8); Anal. calcd. for C20H20O5 (340.13): C 70.57, H 5.92; found: C 70.87, H 5.91. O
O
Methyl 3-(2-methoxybenzyl)-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4h Prepared following general procedure, at room temperature, using benzaldehyde (1.0 mL, 10 mmol, 1 eq.) and 2-bromoanisole (0.94 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4hA and 4hB were obtained in a H 43 : 57 ratio as a colorless solid, mp: 73°C; yield: 2.43 g (71 %); Rf: 0.25 (pentane/diethyl ether mixture OMe CO2Me (7:3)); 1H NMR (CDCl3): δ = 2.54 (1HB, d, J 13.7), 2.72 (1HA, d, J 17.6), 2.73 (1HB, d, J 13.7), 2.77 (1HB, d, J 17.6), 3.01 (1HA, d, J 17.6), 3.08 (1HB, d, J 17.6), 3.34 (1HA, d, J 13.3), 3.34 (3HA, s), 3.38 (1HA, d, J 13.3), 3.76 (3HB, s), 3.77 (3HB, s), 3.85 (3HA, s), 5.50 (1HA, s), 5.75 (1HB, s), 6.79-6.83 (2HA+B, m), 6.92-6.94 (3HA+B, m), 7.107.12 (1HA, m), 7.17-7.18 (1HA, m), 7.19-7.21 (1HB, m), 7.22-7.27 (10HA+B, m); 13C NMR (CDCl3): δ = 31.8 (1CB), 33.6 (1CA), 35.3 (1CA), 36.0 (1CB), 52.0 (1CA), 52.7 (1CB), 55.0 (1CB), 55.2 (1CA), 56.2 (1CB), 58.0 (1CA), 85.6 (1CB), 86.5 (1CA), 110.3 (1CA), 110.7 (1CB), 120.5 (1CB), 120.8 (1CA), 124.1 (1CB), 124.2 (1CA), 126.7 (1CA), 128.2 (1CB), 128.3-128.8 (10CA+B), 131.2 (1CB), 131.6 (1CA), 134.5 (1CA), 135.3 (1CB), 157.5 (1CB), 157.6 (1CA), 171.5 (1CA), 173.2 (1CB), 175.0 (1CB), 175.3 (1CA); IR: ν = 753, 893, 1014, 1171, 1245, 1494, 1732, 1788, 2361, 2901, 2988 cm-1; MS (EI): m/z = 341 (6), 340 (22), 290 (7), 281 (7), 280 (7), 263 (8), 262 (6), 235 (19), 234 (100), 233 (16), 219 (34), 206 (7), 203 (16), 202 (12), 191 (13), 187 (10), 175 (30), 174 (77), 159 (8), 147 (6), 146 (7), 145 (9), 132 (6), 131 (14), 126 (54), 123 (8), 122 (73), 121 (37), 115 (7), 105 (5), 93 (10), 91 (32), 77 (8), 65 (8); Anal. calcd. for C20H20O5 (340.13): C 70.57, H 5.92; found: C 70.31, H 5.99. O
O
ACCEPTED MANUSCRIPT
Methyl 3-(benzo[d][[1,3]]dioxol-5-ylmethyl)-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4i Prepared following general procedure, using benzaldehyde (0.5 mL, 5 mmol, 1 eq.) and 4-bromo-1,3dioxole (0.90 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4iA and 4iB were obtained in a 37 : 63 ratio H as a yellow oil ; yield: 0.59 g (33 %); Rf: 0.14 (pentane/diethyl ether mixture (7:3)); 1H NMR (CDCl3): δ CO2 Me = 2.07 (1HB, d, J 13.9), 2.65-2.72 (3HB, m), 2.83 (1HA, d, J 13.8), 2.99 (1HA, d, J 17.5), 3.10 (1HB, d, J 17.6), 3.28 (3HA, s), 3.49 (1HA, d, J 13.8), 3.74 (3HB, s), 5.36 (1HA, s), 5.68 (1HB, s), 5.82 (2HA, s), 5.86 (2HB, s), 6.35-6.40 (3HA, m), 6.58-6.67 (3HB, m), 7.22-7.48 (10HA+B, m); 13C NMR (CDCl3): δ = 35.3 (1CB), 35.5 (1CA), 38.7 (1CB), 40.3 (1CA), 52.1 (1CA), 52.9 (1CB), 56.3 (1CB), 58.4 (1CA), 85.5 (1CB), 87.0 (1CA), 101.1 (2CA+B), 107.8 (1CB), 108.0 (1CA), 109.6 (1CB),, 110.0 (1CA), 122.8 (1CB), 123.2 (1CA), 125.5 (2CA), 125.8 (2CB), 128.2 (2CA), 128.5 (2CB), 129.1 (1CB), 129.2 (1CA), 134.8 (1CB), 135.0 (1CA), 146.7 (1CB), 146.9 (1CA), 147.8 (2CB), 147.9 (2CA), 170.9 (1CA), 172.9 (1CB), 174.5 (1CB), 174.6 (1CA); IR: ν = 701, 753, 925, 1012, 1034, 1167, 1245, 1443, 1489, 1730, 1785, 2953 cm-1; MS (EI): m/z = 355 (23), 354 (100), 277 (6), 248 (15), 221 (6), 220 (33), 216 (9), 189 (14), 188 (6), 161 (12), 160 (36), 159 (6), 136 (28), 135 (74), 131 (6), 103 (7), 102 (8), 79 (5), 77 (16), 51 (5); HRMS: m/z (ESI) calcd. for C20H18O6Na (M+22.9898): 377.09956; found: 377.09980. O
O
O
RI PT
O
Methyl 5-oxo-2-phenyl-3-(3,4,5-trimethoxybenzyl)tetrahydrofuran-3-carboxylate 4j
Prepared following general procedure, using benzaldehyde (0.5 mL, 5 mmol, 1 eq.) and 3,4,5trimethoxybromobenzene (1.82 g, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4jA and 4jB were obtained O OMe H in a 64 : 36 ratio as a yellow oil; global yield: 1.12 g (56%); Rf: 0.06 (pentane/diethyl ether mixture (7:3)); 1H NMR (CDCl3): δ = 2.22 (1HB, d, J 13.8), 2.84-2.97 (4HA+B, m) 3.17 (1HA, d, J 17.6), 3.29 CO2Me (1HB, d, J 17.7), 3.41 (3HB, s), 3.66 (1HA, d, J 13.8), 3.84 (9HB, s), 3.87 (9HA, s), 3.89 (3HA, s), 5.54 (1HA, s), 5.83 (1HB, s), 6.24 (2HB, s), 6.44 (2HA, s), 7.33-7.50 (10HA+B, m); 13C NMR (CDCl3): δ = 36.1 (1C, C4B), 36.5 (1C, C6A), 39.1 (1C, C6B), 41.0 (1C, C4A), 52.2 (1C, C14A), 53.0 (1C, C14B), 56.2 (3CA), 58.5 (2CA+B), 61.0 (3CB), 86.0 (1CB), 87.8 (1CA), 106.5 (2CB), 106.9 (2CA), 125.8 (1CA), 126.1 (1CB), 128.6 (4CA+B), 129.1 (2CB), 129.3 (2CA), 131.3 (2CA+B), 133.9 (1CB), 134.5 (1CA), 136.9 (1CB), 137.1 (1CA), 153.1 (2CB), 153.2 (2CA), 170.8 (1CA), 172.9 (1CB), 175.6 (1CB), 176.1 (1CA); IR: ν = 702, 756, 1011, 1124, 1222, 1362, 1423, 1456, 1590, 1704, 1790, 2942 cm-1; MS (EI): m/z = 401 (8), 400 (29), 235 (6), 207 (11), 191 (7), 183 (12), 182 (100), 181 (40), 167 (16), 152 (6), 151 (28), 148 (10), 139 (5), 77 (7); HRMS: m/z (ESI) calcd. for C22H24O7Na (M+22.9898): 423.14142; found: 423.14153. OMe
M AN U
SC
MeO O
Methyl 2-(4-fluorophenyl)-3-(4-methoxybenzyl)-5-oxotetrahydrofuran-3-carboxylate 4k Prepared following general procedure, using 4-fluorobenzaldehyde (1.24 g, 10 mmol, 1 eq.) and 4bromoanisole (1.8 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4kA and 4kB were obtained in a 50 : 50 H ratio as a colorless oil; yield: 3.51 g (98 %); Rf: 0.14 (pentane/diethyl ether mixture (7:3)); 1H NMR (CDCl3): δ = 2.16 (1HB, d, J 15.0), 2.70 (1HB, d, J 17.6), 2.71 (1HA, d, J 17.8), 2.78 (1HB, d, J 15.0), CO2 Me F 2.90 (1HA, d, J 13.9), 3.02 (1HB, d, J 17.6), 3.13 (1HA, d, J 17.8), 3.35 (3HA, s), 3.53 (1HA, d, J 13.9), 3.73 (3HB, s), 3.75 (6HA+B, s), 5.40 (1HA, s), 5.69 (1HB, s), 6.76 (2HB, d, J 8.7), 6.83 (2HA, d, J 8.5), 6.87 (2HB, d, J 8.6), 7.07 (2HA, d, J 8.7), 7.06 (2HA, t, J 8.7), 7.13 (2HB, t, J 8.7), 7.27 (4HA+B, m); 13C NMR (CDCl3): δ = 35.6 (1CB), 35.8 (1CA), 38.0 (1CB), 39.9 (1CA), 52.1 (1CA), 52.8 (1CB), 55.2 (2CA+B), 56.3 (1CA), 58.2 (1CB), 84.3 (1CA), 86.3 (1CB), 114.0 (4CA+B), 115.5 (2CA, d, J 18.2), 115.7 (2CB, d, J 21.7), 127.3 (2CA+B), 127.7 (2CA, d, J 8.4), 128.4 (2CB, d, J 8.3), 130.1 (2CA+B, d, J 3.1), 130.9 (4CA+B), 158.9 (2CA+B), 163.0 (1CA, d, J 248.4), 163.1 (1CB, d, J 248.2), 170.9 (1CA), 172.8 (1CB), 174.2 (1CA), 174.4 (1CB); 19 F NMR (CDCl3): δ = -112.1 (2FA+B); IR: ν = 822, 842, 1010, 1020, 1234, 1359, 1609, 1671, 3002 cm-1; MS (EI): m/z = 359 (10), 358 (45), 234 (24), 207 (8), 206 (42), 202 (12), 175 (10), 174 (8), 147 (19), 146 (29), 145 (6), 131 (7), 123 (7), 122 (15), 121 (100), 91 (8), 77 (6); Anal. calcd. for C20H19FO5 (358.12): C 67.03, H 5.34; found: C 67.43, H 5.55. OMe
O
AC C
EP
TE D
O
Methyl 3-(4-methoxybenzyl)-5-oxo-2-(4-(trifluoromethyl)phenyl)tetrahydrofuran-3-carboxylate 4l Prepared following general procedure, using 4-trifluoromethylbenzaldehyde (0.7 mL, 5 mmol, 1 eq.) and 4-bromoanisole (0.9 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4lA and 4lB were obtained in a H 50 : 50 ratio as a colorless oil; yield: 1.36 g (67%); Rf: 0.17 (pentane/diethyl ether mixture (7:3)); 1H CO2 Me NMR (CDCl3): δ = 1.94 (1HA, d, J 14.1), 2.50 (3HA+B, m), 2.71 (1HB, d, J 14.6), 2.78 (1HA, d, J 17.5), F3C 2.93 (1HB, d, J 17.8), 3.09 (3HA, s), 3.32 (1HB, d, J 14.6), 3.51 (3HB, s), 3.54 (3HA, s), 3.56 (3HB, s), 5.23 (1HA, s), 5.53 (1HB, s), 6.53 (2HA, d, J 6.8), 6.61 (4HA+B, m), 6.83 (2HB, d, J 8.6), 7.19 (2HA, d, J 8.2), 7.30 (2HA, d, J 8.2), 7.41 (2HB, d, J 8.2), 7.43 (2HB, d, J 8.2); 13C NMR (CDCl3): δ = 35.7 (1CB), 36.0 (1CA), 37.9 (1CA), 39.8 (1CB), 52.1 (1CA), 52.9 (1CB), 55.1 (1CA), 55.2 (1CB), 56.0 (1CB), 58.4 (1CA), 84.5 (1CB), 86.0 (1CA), 114.0 (2CA), 114.2 (2CB), 125.5 (4CA+B, q, J 6.4), 126.3 (2CA), 126.4 (2CA+B), 126.9 (1CA, q, J 239.9), 127.0 (1CB, q, J 240.0), 127.1 (2CB), 130.6 (2CA), 130.9 (2CB), 131.6 (2CA+B, q, J 27.4), 138.3 (1CA), 139.1 (1CB), 158.8 (1CA), 159.0 (1CB), 170.7 (1CA), 172.6 (1CB), 174.0 (1CA), 174.2 (1CB); 19F NMR (CDCl3): δ = -62.6 (6FA+B); IR: ν = 839, 1012, 1068, 1115, 1166, 1325, 1512, 1698, 1732, 2956 cm-1; MS (EI): m/z = 408 (18), 146 (6), 122 (10), 121 (100), 91 (8), 77 (7); HRMS: m/z (ESI) calcd. for C21H19F3O5Na (M+22.9898): 431.10768; found: 431.10804. O
O
OMe
ACCEPTED MANUSCRIPT
Methyl 3-(4-methoxybenzyl)-5-oxo-2-(3-trifluoromethyl)phenyl)tetrahydrofuran-3-carboxylate 4m Prepared following general procedure, using 3-trifluoromethylbenzaldehyde (0.70 mL, 5 mmol, 1 eq.) and 4-bromoanisole (0.9 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4mA and 4mB were obtained O H in a 64 : 36 ratio as a colorless oil; yield: 1.43 g (78%); Rf: 0.20 (pentane/diethyl ether mixture F3C CO2Me (7:3)); 1H NMR (CDCl3): δ = 2.17 (1HB, d, J 13.8), 2.70 (3HA+B, m), 2.90 (1HA, d, J 13.8), 2.97 (1HA, d, J 17.5), 3.15 (1HB, d, J 17.8), 3.32 (3HA, s), 3.51 (1HA, d, J 13.8), 3.71 (3HB, s), 3.74 (3HA, s), 3.76 (3HB, s), 5.43 (1HA, s), 5.71 (1HB, s), 6.73 (2HB, d, J 8.6), 6.82 (4HA+B, m), 7.03 (2HA, d, J 8.6), 7.44-7.56 (8HA+B, m); 13C NMR (CDCl3): δ = 35.8 (1CB), 35.9 (1CA), 37.7 (1CB), 39.7 (1CA), 52.1 (1CA), 52.9 (1CB), 55.1 (1CA), 55.2 (1CB), 56.0 (1CB), 58.4 (1CA), 84.4 (1CB), 85.9 (1CA), 114.1 (2CB), 114.2 (2CA), 122.9 (1CA, q, J 3.8), 123.7 (1CB, q, J 3.8), 125.8 (1CA, q, J 3.7), 126.9 (1CB), 127.1 (1CA), 128.4 (1CB, q, J 290.8), 128.6 (1CA, q, J 290.8), 129.2 (1CB, q, J 3.9), 130.0 (2CA+B), 130.5 (2CA+B), 130.6 (2CB), 130.9 (2CA), 131.1 (1CB, q, J 23.7), 131.4 (1CA, q, J 23.7), 135.4 (1CB), 136.2 (1CA), 158.9 (1CB), 159.0 (1CA), 170.7 (1CA), 172.4 (1CB), 173.9 (1CB), 174.1 (1CA); 19F NMR (CDCl3): δ = -62.6 (6FA+B); IR: ν = 702, 804, 1022, 1074, 1123, 1166, 1330, 1513, 1612, 1732, 2955 cm-1; MS (EI): m/z = 407 (18), 146 (7), 145 (6), 122 (9), 121 (100), 91 (9), 77 (8); HRMS: m/z (ESI) calcd. for C21H19F3O5Na (M+22.9898): 431.10768; found: 431.10807.
RI PT
OMe
O
Methyl 3-(4-methoxybenzyl)-5-oxo-2-(2-trifluoromethyl)phenyl)tetrahydrofuran-3-carboxylate 4n
Prepared following general procedure, using 2-trifluoromethylbenzaldehyde (1.92 mL, 10 mmol, 1 eq.) and 4-bromoanisole (1.8 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4nA and 4nB were obtained in a H 75 : 25 ratio as a colorless oil; yield: 2.30 g (56 %); Rf: 0.17 (pentane/diethyl ether mixture (7:3)); 1H CO2 Me NMR (CDCl3): δ = 2.15 (1HB, d, J 13.7), 2.86 (1HB, d, J 18.3), 2.88 (1HA, d, J 17.8), 2.97 (1HA, d, J CF3 13.8), 3.03 (1HB, d, J 13.7), 3.12 (1HA, d, J 17.8), 3.29 (3HA, s), 3.37 (1HB, d, J 18.3), 3.59 (1HA, d, J 13.8), 3.76 (3HB, s), 3.79 (3HB, s), 3.80 (3HA, s), 5.93 (1HA, s), 6.23 (1HB, s), 6.81 (2HA, d, J 8.5), 6.84 (2HB, d, J 8.5), 6.92 (2HB, d, J 8.5), 7.06 (2HA, d, J 8.5), 7.35-7.85 (8HA+B, m); 13C NMR (CDCl3): δ = 35.4 (1CB), 36.0 (1CA), 37.8 (1CB), 41.5 (1CA), 51.9 (1CA), 52.8 (1CB), 55.0 (1CB), 56.7 (1CA), 58.3 (2CA+B), 81.2 (1CB), 82.5 (1CA), 113.9 (2CB), 114.1 (2CA), 123.9 (1CB, q, J 274.2), 124.0 (1CA, q, J 274.2), 126.1 (1CA, q, J 5.5), 126.7 (1CB, q, J 5.4), 127.1 (1CB),, 127.5 (1CA), 127.8 (1CA), 128.0 (1CB), 128.8 (1CA, q, J 28.6), 128.9 (1CB, q, J 28.7), 129.3 (1CA), 129.5 (1CB),, 130.3 (2CB), 130.6 (2CA), 132.0 (1CA), 132.3 (1CB), 133.7 (1CB, q, J 2.5), 134.7 (1CA, q, J 2.5),158.7 (1CA), 158.9 (1CB), 171.1 (1CA), 172.8 (1CB), 174.1 (1CA), 174.4 (1CB); 19F NMR (CDCl3): δ = -56.7 (6FA+B); IR: ν = 736, 769, 1009, 1161, 1206, 1513, 1735, 1791, 2955 cm-1; MS (EI): m/z = 408 (11), 207 (7), 146 (6), 122 (9), 121 (100); Anal. calcd. for C21H19F3O5 (408.12): C 61.76, H 4.69; found: C 61.85, H 4.76. OMe
O
M AN U
SC
O
Methyl 3-benzyl-5-oxo-2-(3,4,5-trimethoxyphenyl)tetrahydrofuran-3-carboxylate 4o Prepared following general procedure, using 3,4,5-trimethoxybenzaldehyde (0.98 g, 5 mmol, 1 eq.) and bromobenzene (0.8 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4oA and 4oB were obtained in a 50 : H MeO 50 ratio as a yellow oil; yield: 1.92 g (96%); Rf: 0.05 (pentane/diethyl ether mixture (7:3)); 1H NMR CO2Me (CDCl3): δ = 2.36 (1HB, d, J 13.6), 2.88-2.96 (3HA+B, m), 3.04-3.09 (2HA+B, m), 3.30 (1HA, d, J 18.2), MeO 3.43 (3HA, s), 3.59 (1HA, d, J 13.6), 3.66 (3HB, s), 3.90 (12HA+B, s), 3.92 (6HA+B, s), 5.63 (1HA, s), 5.85 OMe (1HB, s), 6.55 (2HA, s), 6.65 (2HB, s), 7.00-7.30 (10HA+B, m); 13C NMR (CDCl3): δ = 36.5 (1CA), 37.9 (1CB), 38.6 (1CB), 39.7 (1CA), 52.6 (1CA), 53.1 (1CB), 56.2 (1CB), 56.6 (6CA+B), 58.8 (1CA), 87.1 (1CB), 89.2 (1CA), 103.0, (2CA), 103.8 (2CB), 127.4 (1CA), 127.5 (1CB), 128.7 (2CA), 128.9 (2CB), 129.2 (2CA+B), 129.6 (2CB), 129.8 (2CA) 135.2 (1CB), 135.4 (1CA), 137.9 (1CB), 138.0 (1CA), 153.1 (4CA+B) 170.8 (1CA), 172.6 (1CB), 178.5 (1CB), 179.5 (1CA); IR: ν = 575, 700, 978, 1122, 1231, 1717, 2950 cm-1; MS (EI): m/z = 277 (33), 205 (9), 204 (57), 198 (12), 197 (45), 196 (63), 195 (7), 181 (22), 176 (33), 172 (17), 169 (11), 145 (7), 144 (9), 117 (15), 116 (17), 115 (15), 91 (7); HRMS: m/z (ESI) calcd. for C22H24O7Na (M+22.9898): 423.14142; found: 423.14168. O
EP
TE D
O
AC C
Methyl 3-(4-methoxybenzyl)-5-oxo-2-(3,4,5-trimethoxyphenyl)tetrahydrofuran-3-carboxylate 4p Prepared following general procedure, using 3,4,5-trimethoxybenzaldehyde (0.98 g, 5 mmol, 1 eq.) and 4-bromoanisole (0.9 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4pA and 4pB were obtained in H a 52 : 48 ratio as a pink oil; yield: 1.69 g (78%); Rf: 0.13 (pentane/diethyl ether mixture (7:3)); 1H MeO CO2Me NMR (CDCl3): δ = 2.17 (1HA, d, J 14.0), 2.64-2.72 (2HA+B, m), 2.81-2.87 (2HA+B, m), 2.99 (1HB, d, J MeO 17.5), 3.09 (1HA, d, J 17.7), 3.53 (1HB, d, J 14.0), 3.65-3.84 (30HA+B, m), 5.31 (1HA, s), 5.64 (1HB, s), OMe 6.45 (2HA, s), 6.53 (2HB, s), 6.73 (2HA, d, J 8.7), 6.80 (2HB, d, J 8.7), 6.86 (2HA, d, J 8.7), 7.04 (2HB, d, J 8.7); 13C NMR (CDCl3): δ = 35.8 (1CA), 36.2 (1CB), 37.8 (1CA), 40.0 (1CB), 52.2 (1CA), 52.9 (1CB), 55.2 (2CA+B), 56.3 (4CA+B), 58.4 (2CA+B), 60.8 (1CA), 60.9 (1CB), 85.6 (1CB), 87.2 (1CA), 103.0 (2CA), 103.5 (2CB), 113.6 (2CB), 114.0 (2CA), 127.4 (2CA+B), 129.2 (1CA), 129.4 (1CB), 130.6 (2CB), 130.9 (2CA), 138.3 (1CB), 138.4 (1CA), 153.3 (2CA), 153.4 (2CB), 158.8 (1CB), 158.9 (1CA), 171.0 (1CA), 173.0 (1CB), 174.7 (1CB), 174.8 (1CA); IR: ν = 586, 600, 1024, 1508, 1975, 2343, 2364, 2950 cm-1; MS (EI): m/z = 431 (29), 430 (100), 309 (13), 277 (45), 234 (43), 233 (31), 207 (19), 206 (61), 205 (25), 202 (15), 198 (11), 196 (20), 181 (15), 174 (12), 169 (12), 147 (28), 146 (33), 145 (18), 135 (11), 121 (15); HRMS: m/z (ESI) calcd. for C23H26O8Na (M+22.9898): 453.15199; found: 453.15217. O
O
OMe
ACCEPTED MANUSCRIPT Methyl 3-(3-methoxybenzyl)-5-oxo-2-(3,4,5-trimethoxyphenyl)tetrahydrofuran-3-carboxylate 4q Prepared following general procedure, using 3,4,5-trimethoxybenzaldehyde (0.98 g, 5 mmol, 1 eq.) and 3-bromoanisole (0.94 mL, 7.5 mmol, 1.5 eq.). Diastereoisomers 4qA and 4qB were H MeO obtained in a 45 : 55 ratio as a yellow oil; yield: 1.57 g (73 %); Rf: 0.04 (pentane/diethyl ether CO2Me mixture (7:3)); 1H NMR (CDCl3): δ = 2.20 (1HA, d, J 13.7), 2.71-2.93 (5HA+B, m), 3.12 (1HA, MeO d, J 17.9), 3.35 (3HA, s), 3 31 (3HB, s), 3.51 (1HB, d, J 13.5), 3.60-3.83 (24HA+B, m), 5.36 OMe (1HA, s), 5.64 (1HB, s), 6.44-6.52 (6HA+B, m), 6.63-6.74 (4HB, m), 7.07-7.16 (2HA, m); 13C NMR (CDCl3): δ = 36.0 (1CA), 36.8 (1CB), 37.6 (1CA), 40.3 (1CB), 52.3 (2CA+B), 52.9 (2CA+B), 55.2 (2CA), 56.2 (1CB), 56.4 (2CB), 58.3 (1CA), 61.0 (2CA+B), 85.8 (1CB), 87.6 (1CA), 103.0 (2CA), 103.7 (2CB), 112.5 (2CA+B), 115.4 (1CB), 115.7 (1CA), 121.8 (1CB), 122.1 (1CA), 129.6 (1CB), 129.8 (1CA), 130.1 (2CA+B), 137.0 (2CA+B), 138.2 (1CA), 138.4 (1CB), 153.2 (2CA), 153.3 (2CB), 159.7 (1CB), 159.8 (1CA), 171.0 (1CA), 172.9 (1CB), 175.5 (1CA), 175.9 (1CB); IR: ν = 700, 922, 1003, 1124, 1156, 1222, 1331, 1425, 1461, 1509, 1593, 1709, 1787, 2947 cm-1; MS (EI): m/z = 431 (23), 430 (100), 309 (33), 281 (19), 277 (59), 234 (37), 219 (15), 209 (17), 208 (15), 207 (66), 202 (14), 197 (20), 196 (45), 191 (16), 181 (22), 175 (51), 174 (23), 147 (18), 146 (33), 122 (35); HRMS: m/z (ESI) calcd. for C23H26O8Na (M+22.9898): 453.15199; found: 453.15208. O
O
RI PT
OMe
Methyl 3-(2-methoxybenzyl)-5-oxo-2-(3,4,5-trimethoxyphenyl)tetrahydrofuran-3-carboxylate 4r
Prepared following general procedure, at room temperature, using 3,4,5trimethoxybenzaldehyde (0.98 g, 5 mmol, 1 eq.) and 2-bromoanisole (0.94 mL, 7.5 mmol, H MeO 1.5 eq.). Diastereoisomers 4rA and 4rB were obtained in a 50 : 50 ratio as a yellow oil; yield: OMe CO2 Me 2,13 g (98 %); Rf: 0.01 (pentane/diethyl ether mixture (7:3)); 1H NMR (CDCl3): δ = 2.59 (1HA, MeO d, J 13.6), 2.70-2.77 (4HA+B, m), 2.97 (1HB, d, J 17.5), 3.07 (1HA, d, J 17.7), 3.35 (4HB, m), 3.74OMe 3.89 (27HA+B, m), 5.43 (1HA, s), 5.70 (1HB, s), 6.55 (2HA, s), 6.62 (2HB, s), 6.79-6.94 (5HA+B, m), 7.07 (1HB, m), 7.17-7.27 (2HA+B, m); 13C NMR (CDCl3): δ = 31.5 (1CA), 33.4 (1CB), 35.8 (1CB), 36.1 (1CA), 52.2 (1CB), 52.7 (1CA), 55.1 (1CA), 55.2 (1CB), 56.2 (4CA+B), 58.1 (2CA+B), 60.9 (2CA+B), 85.7 (1CB), 86.7 (1CA), 103.0 (2CA), 103.8 (2CB), 110.4 (1CA), 110.8 (1CB), 120.5 (1CA), 120.9 (1CB), 123.9 (1CA), 124.1 (1CB),128.6 (1CA), 128.9 (1CB), 129.9 (1CA), 130.6 (1CB), 131.2 (1CA), 131.6 (1CB), 138.2 (1CA), 138.4 (1CB), 153.2, (4CA+B), 157.5 (1CA), 157.6 (1CB), 171.5 (1CA), 173.2 (1CB), 175.5 (1CA), 175.9 (1CB); IR: ν = 729, 1125, 1242, 1509, 1732, 1787, 2943 cm-1; MS (EI): m/z = 431 (22), 430 (100), 309 (26), 308 (13), 281 (22), 277 (46), 234 (39), 209 (21), 208 (21), 207 (96), 206 (11), 196 (22), 191 (19), 181 (15), 175 (30), 174 (30), 131 (24), 126 (39), 121 (34), 91 (23); HRMS: m/z (ESI) calcd. for C23H26O8Na (M+22.9898): 453.15199; found: 453.15221.
SC
O
M AN U
O
TE D
Methyl 3-(benzo[d][[1,3]]dioxol-5-ylmethyl)-5-oxo-2-(3,4,5-trimethoxyphenyl)tetrahydrofuran-3-carboxylate 4s Prepared following general procedure, using 3,4,5-trimethoxybenzaldehyde (0.98 g, 5 mmol, 1 eq.) and 4-bromobenzo[1,3]dioxole (0.9 mL, 7.5 mmol, 1.5 eq.). Diastereoisomers 4sA and 4sB O O H were obtained in a 79 : 21 ratio as a yellow oil; yield: 0.93 g (42 %); Rf: 0.04 (pentane/diethyl MeO CO2 Me ether mixture (7:3)); 1H NMR (CDCl3): δ = 2.12 (1HB, d, J 13.9), 2.70 (2HA+B, m) 2.82 (2HA+B, MeO m), 3.00 (1HA, d, J 17.8), 3.12 (1HB, d, J 17.7), 3.38 (3HB, s), 3.52 (1HA, d, J 13.9), 3.60-3.86 OMe (18HA+B, m), 4.39 (3HB, s), 5.32 (1HA, s), 5.64 (1HB, s), 5.82-5.90 (4HA+B, m), 6.44 (2HA, s), 6.23-6.71 (8HA+B, m); 13C NMR (CDCl3): δ = 36.2 (2CA+B), 40.5 (2CA+B), 52.3 (1CA), 52.6 (1CB), 56.1 (2CA), 56.3 (1CB), 56.4 (2CB), 58.4 (2CA+B), 60.9 (1CA), 87.4 (2CA+B), 100.8 (1CA), 101.2 (1CB), 105.7 (2CB), 108.0 (2CA), 108.5 (1CB), 108.6 (1CA), 109.9 (2CA+B), 121.4 (1CA), 121.5 (1CB), 129.0 (1CA), 130.2 (1CB), 136.7 (1CA), 137.2 (1CB), 138.9 (1CB), 140.2 (1CA), 145.7 (1CA), 147.0 (1CB), 147.5 (1CA), 148.0 (1CB), 152.7 (2CA), 153.3 (2CB), 170.9 (4CA+B); IR: ν = 730, 1037, 1223, 1361, 1423, 1490, 1505, 1592, 1698 cm-1; MS (EI): m/z = 445 (25), 444 (100), 309 (14), 281 (9), 277 (31), 249 (9), 248 (49), 247 (20), 220 (48), 219 (20), 216 (13), 207 (22), 197 (11), 196 (14), 189 (23), 181 (13), 169 (11), 161 (16), 160 (33), 35 (14); HRMS: m/z (ESI) calcd. for C23H24O9Na (M+22.9898): 467.13125; found: 467.13169. O
AC C
EP
O
Methyl 5-oxo-3-(3,4,5-trimethoxybenzyl)-2-(3,4,5-trimethoxyphenyl)tetrahydrofuran-3-carboxylate 4t Prepared following general procedure, using 3,4,5-trimethoxybenzaldehyde (0.98 g, 5 mmol, 1 eq.) and 3,4,5-trimethoxybromobenzene (1.82 g, 7.5 mmol, 1.5 eq.). Diastereoisomers 4tA and O OMe H 4tB were obtained in a 54 : 46 ratio as a yellow oil; yield: 1.36 g (56 %); Rf: 0.20 MeO (pentane/diethyl ether mixture (7:3)); 1H NMR (CDCl3): δ = 2.14 (1HA, d, J 13.9), 2.66 (1HA, CO2Me d, J 17.6), 2.70 (1HB, d, J 17.5), 2.79 (1HB, d, J 13.7), 2.83 (1HA, d, J 13.9), 2.99 (1HB, d, J MeO OMe 17.5), 3.13 (1HA, d, J 17.6), 3.36 (3HA, s), 3.57 (1HB, d, J 13.7), 3.72-3.85 (39HA+B, m), 5.29 (1HA, s), 5.61 (1HB, s), 6.14 (2HB, s), 6.30 (2HA, s), 6.42 (2HA, s), 6.50 (2HB, s); 13C NMR (CDCl3): δ = 36.0 (1CB), 36.2 (1CA), 38.7 (1CA), 41.3 (1CB), 52.3 (1CA), 52.9 (1CB), 56.1-56.3 (8CA+B), 58.4 (2CA+B), 60.8 (2CB), 60.9 (2CA), 85.5 (1CB), 87.3 (1CA), 102.9 (2CA), 103.5 (2CB), 106.6 (2CB), 106.8 (2CA), 129.5 (2CA+B), 130.2 (1CB), 131.2 (1CA), 137.3 (1CA), 137.4 (1CB), 138.3 (1CB), 138.5 (1CA), 153.1-153.4 (8CA+B), 170.9 (1CA), 172.9 (1CB), 174.4 (2CA+B); IR: ν = 693, 843, 1004, 1122, 1236, 1330, 1422, 1460, 1591, 1709, 1788, 2839, 2942 cm-1; MS (EI): not detected; HRMS: m/z (ESI) calcd. for C25H30O10Na (M+22.9898): 513.17312; found: 513.17331. MeO O
OMe
ACCEPTED MANUSCRIPT Methyl 2-(furan-2-yl)-3-(4-methoxybenzyl)-5-oxotetrahydrofuran-3-carboxylate 4u Prepared following general procedure, using furaldehyde (0.83 mL, 10 mmol, 1 eq.) and 4bromoanisole (1.8 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4uA and 4uB were obtained in a 60 : H 40 ratio as a colorless oil; yield: 1.62 g (49 %); Rf: 0.24 (pentane/diethyl ether mixture (7:3)); 1H CO2Me NMR (CDCl3): δ = 2.38 (1HB, d, J 13.8), 2.67 (1HB, d, J 17.7), 2.94 (1HA, d, J 13.9), 2.96 (1HB, d, J O 13.8), 3.03 (1HA, d, J 18.6), 3.28 (1HB, d, J 17.7), 3.45 (1HA, d, J 18.6), 3.70 (1HA, d, J 13.9), 3.53 (3HA, s), 3.70 (3HB, s), 3.76 (3HA, s), 3.78 (3HB, s), 5.40 (1HA, s), 5.78 (1HB, s), 6.36-6.37 (1HB, m), 6.42 (1HA, m), 6.42 (1HB, m), 6.55 (1HA, m), 6.79 (2HB, d, J 8.7), 6.88 (2HA, d, J 8.7), 6.89 (2HB, d, J 8.7), 7.04 (2HA, d, J 8.7), 7.40 (1HB, m), 7.51 (1HA, m); 13C NMR (CDCl3): δ = 31.7 (1CB), 34.7 (1CA), 37.4 (1CB), 40.8 (1CA), 51.7 (2CA+B), 52.1 (1CA), 57.1 (1CB), 55.1 (1CA), 56.4 (1CB), 79.6 (2CA+B) 110.1-111.6 (4CA+B), 114.0 (2CA), 114.2 (2CB), 126.8 (1CB), 127.5 (1CA), 127.5 (1CA), 171.6 (1CB), 130.1 (2CA), 130.7 (2CB), 143.7 (2CA+B), 148.5 (2CA+B), 158.9 (2CA+B), 171.0 (1CA), 174.3 (1CB); IR: ν = 786, 885, 962, 996, 1030, 1150, 1210, 1440, 1513, 1711, 2955 cm-1; MS (EI): m/z = 330 (25), 281 (5), 234 (5), 210 (12), 209 (100), 207 (5), 206 (23), 181 (11), 175 (8), 147 (15), 146 (24), 145 (7), 131 (6), 122 (31), 121 (48), 91 (9), 78 (5), 77 (7); Anal. calcd. for C18H18O6 (330.11): C 65.45, H 5.49; found: C 65.68, H 5.43. O
OMe
RI PT
O
Methyl 2-hexyl-3-(4-methoxybenzyl)-5-oxotetrahydrofuran-3-carboxylate 4v
Prepared following general procedure, using heptanal (1.4 mL, 10 mmol, 1 eq.) and 4bromoanisole (1.8 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4vA and 4vB were obtained in O a 12 : 88 ratio as a colorless solid, mp: 55°C; yield: 0.94 g (27 %); Rf: 0.19 (pentane/diethyl CO2Me ether mixture (7:3)); 1H NMR (CDCl3): δ = 0.82-0.91 (6HA+B, m), 1.24-1.36 (16HA+B, m,), 1.51-1.70 (4HA+B, m), 2.56 (1HB, d, J 17.4), 2.58 (1HA, d, J 17.5), 2.59 (1HB, d, J 13.9), 2.76 (1HA, d, J 13.9), 2.84 (1HB, d, J 17.4), 2.95 (1HA, d, J 17.5), 3.33 (1HB, d, J 13.9), 3.37 (1HA, d, J 13.9), 3.73 (3HA, s), 3.75 (3HB, s), 3.78 (6HA+B, s), 4.34 (1HA, d, J 8.4), 4.51 (1HB, d, J 9.4), 6.83 (4HA+B, d, J 8.3), 6.98 (2HA, d, J 8.3), 7.03 (2HB, d, J 8.3); 13C NMR (CDCl3): δ = 14.0 (2CA+B), 22.3 (1CA), 22.5 (1CB), 26.2 (1CA), 26.5 (1CB), 29.0 (1CA), 29.2 (1CB), 30.9 (2CA+B), 31.6 (1CA), 31.8 (1CB), 35.6 (1CB), 36.1 (1CA), 39.7 (2CA+B), 52.3 (1CA), 52.6 (1CB), 55.0 (2CA+B), 55.2 (1CB), 55.6 (1CA), 84.9 (1CA), 85.7 (1CB), 114.0 (4CA+B), 127.4 (1CA), 127.5 (1CB), 130.6 (2CB), 130.9 (2CA), 158.8 (2CA+B), 171.9 (1CB), 172.6 (1CA), 174.6 (2CA+B); IR: ν = 837, 961, 1032, 1177, 1248, 1513, 1732, 1782, 2857 cm-1; MS (EI): m/z = 348 (12), 122 (9), 121 (100); Anal. calcd. for C20H28O5 (348.19): C 68.94, H 8.10; found: C 69.25, H 8.48. OMe
M AN U
SC
O
Methyl 3-benzyl-2-methyl-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4w Prepared following general procedure, using acetophenone (0.58 mL, 5 mmol, 1 eq.) and bromobenzene (0.8 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4wA and 4wB were obtained in a 43 : H3C 57 ratio as a colorless oil; yield: 1.34 g (82 %); Rf: 0.04 (pentane/diethyl ether mixture (7:3)); 1H NMR CO2Me (CDCl3): δ = 1.78 (3HB, s), 2.00 (3HA, s), 2.25 (1HB, d, J 13.7), 2.68-2.98 (5HA+B, m), 3.31 (4HA+B, s), 3.74 (1HA, d, J 13.6), 3.81 (3HB, s), 6.97 (2HB, m), 7.15 (2HA, m), 7.25-7.30 (6HA+B, m), 7.37-7.40 (6HA+B, m), 7.47 (2HB, m), 7.67 (2HB, m); 13C NMR (CDCl3): δ = 23.0 (1CA), 25.3 (1CB), 35.7 (1CB), 35.9 (1CA), 37.7 (1CA), 40.5 (1CB), 52.0 (1CA), 52.5 (1CB), 58.9 (1CB), 60.1 (1CA), 89.3 (1CB), 89.3 (1CA), 125.0 (2CA), 126.1 (2CB), 127.2 (1CB), 127.3 (1CA), 128.2 (2CA), 128.3 (2CB), 128.4 (2CA+B), 129.2 (2CA+B), 128.6 (2CB), 128.7 (2CA), 129.8 (2CB), 130.0 (2CA), 130.5 (1CA), 130.8 (1CB), 171.0 (1CA), 171.9 (1CB), 173.7 (1CB), 174.4 (1CA); IR: ν = 699, 766, 949, 1230, 1728, 1778, 2950 cm-1; MS (EI): m/z = 377 (5), 375 (38), 374 (11), 373 (72), 372 (7), 371 (45), 281 (6), 221 (26), 220 (10), 219 (100), 218 (6), 217 (82), 208 (6), 207 (17), 193 (8), 191 (24), 189 (16), 110 (8), 75 (10), 74 (9); HRMS: m/z (ESI) calcd. for C20H20O4Na (M+22.9898): 347.12538; found: 347.12573. O
EP
TE D
O
AC C
Methyl 3-(4-methoxybenzyl)-2-methyl-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4x Prepared following general procedure, using acetophenone (1.12 g, 10 mmol, 1 eq.) and 4bromoanisole (1.8 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4xA and 4xB were obtained in a 40 : 60 ratio as a colorless solid, mp: 143 °C; yield: 3.00 g (85 %); Rf: 0.27 (pentane/diethyl ether mixture (7:3)); Diastereoisomers were separated as described above (Section 4.3). Diastereoisomer 4xA: 1H NMR (CDCl3): δ = 1.95 (3HA, s), 2.62 (1HA, d, J 18.3), 2.77 (1HA, d, J 13.5), 2.90 (1HA, d, J 18.3), 3.31 (3HA, s), 3.65 (1HA, d, J 13.5), 3.77 (3HA, s), 6.80 (2HA, d, J 8.7), 7.02 (2HA, d, J 8.7), 7.27-7.38 (5HA, m); 13 C NMR (CDCl3): δ = 22.9 (1CA), 35.8 (1CA), 37.0 (1CA), 51.9 (1CA), 55.2 (1CA), 60.2 (1CA), 89.3 (1CA), 114.1 (1CA), 125.0 (1CA), 127.6 (1CA), 128.2 (1CA), 128.4 (1CA), 130.9 (1CA), 140.5 (1CA), 158.8 (1CA), 171.0 (1CA), 174.6 (1CA); Diastereoisomer 4xB: 1H NMR (CDCl3): δ = 1.73 (3HB, s), 2.12 (1HB, d, J 13.5), 2.68-2.74 (2HB, m), 3.24 (1HB, d, J 17.5), 3.74 (3HB, s), 3.81 (3HB, s), 6.75 (2HB, d, J 8.7), 6.84 (2HB, d, J 8.7), 7.34-7.59 (3HB, m), 7.60 (2HB, d, J 8.6); 13C NMR (CDCl3): δ = 25.3 (1CB), 35.6 (1CB), 38.9 (1CB), 52.0 (1CB), 52.5 (1CB), 59.0 (1CB), 89.2 (1CB), 114.0 (1CB), 124.6 (1CB), 127.6 (1CB), 128.2 (1CB), 128.3 (1CB), 130.8 (1CB), 139.2 (1CB), 158.7 (1CB), 172.0 (1CB), 173.8 (1CB); IR: ν = 881, 1088, 1141, 1252, 1735, 2973 cm-1; MS (EI): m/z = 355 (7), 354 (33), 235 (13), 234 (100), 233 (5), 207 (11), 206 (78), 203 (5), 202 (21), 175 (15), 174 (13), 160 (10), 147 (21), 146 (36), 135 (6), 131 (7), 121 (67), 115 (5), 91 (7), 77 (9); Anal. calcd. for C21H22O5 (354.15): C 71.17, H 6.26; found: C 71.19, H 6.35.
ACCEPTED MANUSCRIPT
Methyl 3-(3-methoxybenzyl)-2-methyl-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4y Prepared following general procedure, using acetophenone (0.58 mL, 5 mmol, 1 eq.) and 3bromoanisole (0.95 mL, 7.5 mmol, 1.5 éq). Both diastereoisomers 4yA and 4yB were obtained in a OMe H 3C 40 : 60 ratio as a colorless oil; yield: 0.99 g (60 %); Rf: 0.11 (pentane/diethyl ether mixture (7:3)); 1 CO2Me H NMR (CDCl3): δ = 1.78 (3HA, s), 1.99 (3HB, s), 2.23 (1HB, d, J 13.8), 2.70-2.99 (5HA+B, m), 3.33 (1HB, d, J 16.9), 3.35 (3HA, s), 3.69 (1HA, d, J 16.9), 3.70 (3HB, s), 3.75 (3HA, s), 3.87 (3HB, s), 6.52-6.82 (4HB, m), 7.15-7.24 (4HA, m), 7.33-7.70 (10HA+B, m); 13C NMR (CDCl3): δ = 23.0 (1CB), 30.9 (1CA), 35.6 (1CB), 35.9 (1CA), 37.7 (1CA), 40.5 (1CB), 52.0 (1CA), 52.5 (1CB), 55.1 (2CA+B), 58.8 (1CB), 60.1 (1CA), 89.2 (1CB), 89.3 (1CA), 112.6 (2CA+B), 115.4 (1CA), 115.7 (1CB), 122.1 (1CB), 122.2 (1CA), 125.0 (2CA+B), 126.0 (4CA+B), 128.2 (4CA+B), 129.6 (1CB), 129.7 (1CA), 137.3 (1CB), 137.4 (1CA), 139.2 (1CB), 140.4 (1CA), 159.7 (2CA+B), 171.0 (1CB), 171.9 (1CA), 173.6 (1CB), 174.3 (1CA); IR: ν = 579, 701, 768, 949, 1069, 1248, 1731, 1781, 2951 cm-1; MS (EI): m/z = 355 (5), 254 (19), 235 (16), 234 (100), 219 (16), 206 (13), 203 (6), 202 (16), 176 (6), 175 (58), 174 (31), 147 (15), 146 (28), 145 (6), 131 (7), 115 (6), 103 (6), 91 (9); HRMS: m/z (ESI) calcd. for C21H22O5Na (M+22.9898): 377.13594; found: 377.13633. O
RI PT
O
Methyl 3-(2-methoxybenzyl)-2-methyl-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4z
Prepared following general procedure, at room temperature, using acetophenone (0.58 mL, 5 mmol, 1 eq.) and 2-bromoanisole (0.94 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4zA and 4zB were H3C obtained in a 70 : 30 ratio as a yellow oil; yield: 1.54 g (87 %); Rf: 0.12 (pentane/diethyl ether OMe CO2 Me mixture (7:3)); 1H NMR (CDCl3): δ = 1.69 (3HB, s), 1.96 (3HA, s), 2.35 (1HB, d, J 13.7), 2.57 (1HA, d, J 17.5), 2.69 (1HB, d, J 17.9), 2.79 (1HB, d, J 13.7), 2.81 (1HA, d, J 17.5), 3.21 (1HB, d, J 17.9), 3 31 (3HA, s), 3.34 (1HA, d, J 13.0), 3.40 (1HA, d, J 13.0), 3.74 (3HB, s), 3.78 (3HB, s), 3.81 (3HA, s), 6.74-6.84 (5HA+B, m), 7.02 (1HA, m), 7.13-7.17 (2HA+B, m), 7.28-7.31 (5HA+B, m), 7.39-7.42 (3HA+B, m), 7.55 (2HB, m); 13C NMR (CDCl3): δ = 23.0 (1CA), 25.3 (1CB), 30.5 (1CA), 33.4 (1CB), 35.3 (1CA), 35.6 (1CB), 51.9 (1CA), 52.4 (1CB), 55.1 (1CB), 55.2 (1CA), 59.2 (1CB), 60.3 (1CA), 89.1 (1CB), 89.2 (1CA), 110.4 (1CB), 110.5 (1CA), 120.6 (1CB), 120.7 (1CA), 124.4 (1CB), 124.5 (1CA), 125.1 (2CA), 126.2 (2CB), 128.0 (2CA), 128.1 (2CB), 128.2 (2CA+B), 128.3 (1CA), 128.6 (1CB), 130.6 (1CB), 130.9 (1CA), 139.5 (1CB), 140.8 (1CA), 157.5 (1CB), 157.6 (1CA), 171.4 (1CB), 172.4 (1CA), 174.1 (1CB), 175.1 (1CA); IR: ν = 700, 756, 900, 1007, 1214, 1244, 1439, 1494, 1729, 1781, 2950 cm-1; MS (EI): m/z = 353 (22), 235 (12), 234 (100), 206 (24), 203 (11), 202 (15), 187 (9), 175 (48), 174 (60), 147 (11), 146 (18), 145 (10), 132 (9), 131 (39), 126 (64), 121 (54), 115 (12), 93 (13), 91 (40), 77 (9); HRMS: m/z (ESI) calcd. for C21H22O5Na (M+22.9898): 377.13594; found: 377.13626. O
M AN U
SC
O
Methyl 3-(4-methoxybenzyl)-5-oxo-2-phenyl-2-(trifluoromethyl)tetrahydrofuran-3-carboxylate 4aa Prepared following general procedure, using 2,2,2-trifluoroacetophenone (1.36 mL, 10 mmol, 1 eq.) and 4-bromoanisole (1.8 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4aaA and 4aaB were F3C obtained in a 88 : 12 ratio as a colorless oil; yield: 2.20 g (54 %); Rf: 0.72 (pentane/diethyl ether CO2 Me mixture (7:3)); 1H NMR (CDCl3): δ = 2.04 (1HB, d, J 13.9), 2.71 (1HB, d, J 17.5), 2.78 (1HA, d, J 18.5), 3.03 (1HB, d, J 17.5), 3.02 (1HB, d, J 13.9), 3.10 (3HA, s), 3.17 (1HA, d, J 13.5), 3.56 (1HA, d, J 18.5), 3.69 (3HB, s), 3.76 (3HA, s), 3.87 (1HA, d, J 13.5), 3.88 (3HB, s), 6.76 (2HB, d, J 8.6), 6.80 (2HA, d, J 8.6), 6.86 (2HB, d, J 8.5), 7.15 (2HA, d, J 8.5), 7.42-7.48 (6HA+B, m), 7.61-7.63 (4HA+B, m); 13C NMR (CDCl3): δ = 34.0 (1CB), 34.6 (1CA), 36.5 (1CB), 39.2 (1CA), 51.3 (1CA), 52.2 (1CB), 54.1 (1CA), 55.2 (1CB), 59.1 (2CA+B), 86.9 (1CA, q, J 28.6), 87.5 (1CB, q, J 28.8), 113.0 (2CA), 113.3 (2CB), 123.2 (2CA+B, q, J 288.0), 124.9, (2CB), 125.2 (2CA), 125.9 (1CB), 126.4 (1CA), 127.3, (4CA+B), 128.8, (2CA+B), 129.0 (1CB), 129.5 (1CA), 130.3 (2CA), 130.4 (2CB), 157.9 (1CA), 158.0 (1CB), 168.5 (1CB), 168.8 (1CA), 170.7 (1CA), 170.9 (1CB); 19F NMR (CDCl3): δ = -72.0 (6FA+B); IR: ν = 699, 711, 1028, 1166, 1252, 1513, 1738, 1812, 2957 cm-1; MS (EI): m/z = 408 (13), 233 (6), 205 (5), 146 (6), 145 (6), 122 (8), 121 (100), 91 (6), 77 (6); Anal. calcd. for C21H19F3O5 (408.12): C 61.76, H 4.59; found: C 61.41, H 4.67. O
OMe
AC C
EP
TE D
O
Methyl 3-benzyl-2-ethyl-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4ab Prepared following general procedure, using propiophenone (1.34 mL, 10 mmol, 1 eq.) and bromobenzene (1.9 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4abA and 4abB were obtained in a H3 C-CH2 81 : 19 ratio as a colorless solid, mp: 124°C; yield: 1.76 g (52%); Rf: 0.26 (pentane/diethyl ether CO2Me mixture (7:3)); 1H NMR (CDCl3): δ = 0.85 (3HA, t, J 7.2), 0.91 (3HB, t, J 7.2), 2.10 (1HA, m), 2.15 (1HA, m), 2.25 (1HA, d, J 13.8), 2.29 (1HB, m), 2.55 (1HB, m), 2.76 (1HB, d, J 18.2), 2.80 (1HA, d, J 18.2), 2.85 (1HA, d, J 13.8), 2.89 (1HB, d, J 18.2), 2.99 (1HB, d, J 13.7), 3.35 (3HB, s), 3.40 (1HA, d, J 18.2), 3.73 (1HB, d, J 13.7), 3.89 (3HA, s), 7.01 (1HA, dd, J 1.9, 7.2), 7.20 (1HB, dd, J 1.6, 8.0), 7.21-7.50 (17HA+B, m), 7.70 (1HA, d, J 7.8); 13 C NMR (CDCl3): δ = 8.1 (1CA), 8.4 (1CB), 27.9 (1CB), 30.2 (1CA), 35.7 (1CA), 36.4 (1CB), 37.1 (1CB), 40.7 (1CA), 51.9 (1CB), 52.5 (1CA), 59.1 (1CA), 60.7 (1CB), 92.4 (1CA), 92.4 (1CB), 125.6 (1CB), 126.6 (1CA), 127.2-128.9 (16CA+B), 129.8 (1CA), 130.0 (1CB), 135.8 (1CA), 136.0 (1CB), 136.8 (1CA), 137.9 (1CB), 171.2 (1CB), 171.9 (1CA), 173.7 (1CA), 174.3 (1CB); IR: ν = 688, 749, 948, 962, 1212,1723, 1792, 2944 cm-1; MS (EI): m/z = 309 (23), 277 (7), 263 (7), 249 (13), 205 (20), 204 (100), 177 (9), 176 (73), 173 (7), 172 (53), 145 (16), 144 (20), 134 (17), 117 (45), 116 (39), 115 (42), 105 (38), 91 (38), 77 (19), 65 (8); Anal. calcd. for C21H22O4 (338.15): C 74.54, H 6.55; found: C 74.39, H 6.72. O
O
ACCEPTED MANUSCRIPT
Methyl 2-ethyl-3-(4-methoxybenzyl)-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4ac Prepared following general procedure, using propiophenone (0.67 mL, 5 mmol, 1 eq.) and 4bromoanisole (1.8 mL, 15 mmol, 1.5 eq.). Both diastereoisomers 4acA and 4acB were obtained in a H3 C-CH 2 40 : 60 ratio as a yellow oil; yield: 0.76 g (41 %); Rf: 0.57 (pentane/diethyl ether mixture (7:3)); 1 CO2 Me H NMR (CDCl3): δ = 0.79 (3HB, t, J 7.0), 0.81 (3HA, t, J 7.0), 2.00 (1HB, m), 2.05 (1HB, m), 2.13 (1HB, d, J 13.9), 2.23 (1HA, m), 2.45 (1HA, m), 2.63-2.73 (3HA+B, m), 2.81-2.85 (2HA+B, m), 3.263.31 (4HA, m), 3.63 (1HA, d, J 13.3), 3.73 (3HB, s), 3.75 (3HA, s), 3.80 (3HB, s), 6.74 (2HB, d, J 8.4), 6.79 (2HA, d, J 8.4), 6.84 (2HB, d, J 8.4), 7.03 (2HA, d, J 8.4), 7.35-7.44 (8HA+B, m), 7.58 (2HB, d, J 7.5); 13C NMR (CDCl3): δ = 8.0 (1CB), 8.3 (1CA), 27.8 (1CA), 30.2 (1CB), 34.9 (1CA), 35.7 (2CA+B), 39.8 (1CB), 51.9 (1CA), 52.5 (1CB), 55.1 (1CB), 55.2 (1CA), 59.2 (1CB), 60.8 (1CA), 92.3 (1CA), 92.4 (1CB), 114.0 (4CA+B), 125.6 (2CA), 126.6 (2CB), 127.6 (1CA), 127.9 (1CB), 128.0 (1CA), 128.1 (1CB), 128.2 (2CB), 128.4 (2CA), 130.8 (2CB), 131.0 (2CA), 136.9 (1CB), 137.9 (1CA), 158.7 (2CA+B), 171.2 (1CA), 171.9 (1CB), 173.8 (1CB), 174.4 (1CA); IR: ν = 699, 752, 975, 1223, 1249, 1296, 1512, 1730, 1780, 2950 cm-1; MS (EI): m/z = 369 (8), 368 (30), 235 (7), 234 (59), 207 (20), 206 (20), 202 (15), 175 (11), 174 (6), 160 (8), 147 (16), 146 (27), 135 (10), 122 (8), 121 (100), 115 (6), 103 (7), 91 (14), 77 (13); HRMS: m/z (ESI) calcd. for C22H24O5Na (M+22.9898): 391.15159; found: 391.15182. O
OMe
RI PT
O
Methyl 2-methyl-5-oxo-2-phenyl-3-(4-trifluoromethyl)benzyl)tetrahydrofuran-3-carboxylate 4ad
Prepared following general procedure, using acetophenone (0.58 mL, 5 mmol, 1 eq.) and 4trifluorobromobenzene (1.04 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4adA and 4adB were O H 3C obtained in a 28 : 72 ratio as a yellow oil; yield: 0.43 g (22 %); Rf: 0.30 (pentane/diethyl ether CO2Me mixture (7:3)); 1H NMR (CDCl3): δ = 1.72 (3HB, s), 1.94 (3HA, s), 2.23 (1HB, d, J 13.7), 2.56 (1HA, d, J 17.6), 2.61 (1HB, d, J 18.1), 2.82 (1HB, d, J 13.7), 2.91 (1HA, d, J 13.7), 3.24 (1HA, d, J 17.6), 3.28 (3HA, s), 3.26 (1HB, d, J 18.1), 3.74 (1HA, d, J 13.7), 3.80 (3HB, s), 7.04 (2HB, d, J 8.0), 7.22 (2HA, d, J 8.0), 7.297.47 (10HA+B, m), 7.51 (2HA, d, J 8.0), 7.54 (2HB, d, J 8.0); 13C NMR (CDCl3): δ = 23.1 (1CA), 25.3 (1CB), 35.6 (1CB), 35.8 (1CA), 37.6 (1CA), 40.1 (1CB), 52.2 (1CB), 52.7 (1CA), 58.7 (1CB), 59.9 (1CA), 89.3 (2CA+B), 124.9 (2CA, q, J 3.8), 125.5 (2CA+B), 125.5 (2CB, q, J 3.8), 126.0 (4CA+B), 128.4 (2CB), 128.5 (2CA), 129.5 (1CA, q, J 273.3), 129.6 (1CB, q, J 273.2), 130.2 (4CA+B), 130.3 (2CA+B, q, J 31.0), 139.0 (2CA+B), 140.1 (2CA+B), 170.1 (1CA), 171.6 (1CB), 173.2 (1CB), 173.9 (1CA); 19F NMR (CDCl3): δ = -62.6 (6FA+B); IR: ν = 700, 768, 1067, 1115, 1324, 1731, 1781, 2954 cm-1; MS (EI): m/z = 373 (6), 273 (13), 272 (100), 245 (11), 244 (74), 240 (20), 213 (15), 212 (11), 202 (40), 185 (21), 184 (28), 175 (5), 165 (13), 115 (12), 105 (8), 77 (6); HRMS: m/z (ESI) calcd. for C21H19F3O4Na (M+22.9898): 415.11276; found: 415.11298. CF3
M AN U
SC
O
Methyl 2-methyl-5-oxo-2-phenyl-3-(3-trifluoromethyl)benzyl)tetrahydrofuran-3-carboxylate 4ae Prepared following general procedure, using acetophenone (0.58 mL, 5 mmol, 1 eq.) and 3trifluorobromobenzene (1.04 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4aeA and 4aeB were obtained in a 40 : 60 ratio as a colorless oil; yield: 0.44 g (23 %); Rf: 0.20 (pentane/diethyl ether CO2Me mixture (7:3)); 1H NMR (CDCl3): δ = 1.71 (3HB, s), 1.92 (3HA, s), 2.23 (1HB, d, J 13.7), 2.60 (1HB, d, J 18.1), 2.62 (1HA, d, J 17.6), 2.78 (1HB, d, J 13.7), 2.87 (1HA, d, J 17.6), 2.92 (1HA, d, J 13.3), 3.23 (3HA, s), 3.27 (1HB, d, J 18.1), 3.64 (1HA, d, J 13.3), 3.76 (3HB, s), 7.11-7.57 (18HA+B, m); 13C NMR (CDCl3): δ = 23.1 (1CB), 25.2 (1CA), 35.6 (1CB), 36.1 (1CA), 37.4 (1CA), 42.8 (1CB), 52.0 (1CA), 52.6 (1CB), 58.8 (1CB), 60.1 (1CA), 89.2 (1CB), 89.3 (1CA), 124.3 (1CB, q, J 3.9), 124.9 (2CA+B), 125.3 (1CA, q, J 272.3), 125.5 (1CA, q, J 3.8), 125.6 (1CB, q, J 276.5), 126.0 (2CA+B), 126.4 (1CA, q, J 3.7), 126.6, (1CB, q, J 3.7), 128.2 (2CA), 128.4 (2CB), 129.1 (1CB), 129.2 (1CA), 131.3 (1CA, q, J 31.6), 131.4 (1CA, q, J 32.2), 133.4 (2CA+B), 136.9 (4CA+B), 139.0 (1CB), 140.1 (1CA), 170.7 (1CA), 171.6 (1CB), 173.2 (1CB), 173.8 (1CA); 19F NMR (CDCl3): δ = -61.5 (6FA+B); IR: ν = 573, 956, 1168, 1286, 1736, 1780, 2350, 2791, 2926, 2955 cm-1; MS (EI): m/z = 273 (16), 272 (100), 252 (9), 245 (10), 244 (72), 240 (13), 213 (15), 212 (13), 203 (8), 202 (47), 185 (26), 184 (25), 175 (6), 165 (14), 159 (6), 115 (16), 105 (8), 77 (9); HRMS: m/z (ESI) calcd. for C21H19F3O4Na (M+22.9898): 415.11276; found: 415.11292. CF3
AC C
EP
H 3C
TE D
O
O
Methyl 2-methyl-5-oxo-2-phenyl-3-(2-trifluoromethyl)benzyl)tetrahydrofuran-3-carboxylate 4af Prepared following general procedure, at room temperature, using acetophenone (0.58 mL, 5 mmol, 1 eq.) and 2-trifluorobromobenzene (1.4 mL, 10 mmol, 2 eq.). Both diastereoisomers 4afA and 4afB H 3C were obtained in a 63 : 37 ratio as a colorless oil; yield: 0.30 g (15 %); Rf: 0.38 (pentane/diethyl ether CF3 CO2Me mixture (7:3)); 1H NMR (CDCl3): δ = 1.61 (3HB, s), 1.83 (3HA, s), 2.40 (1HB, d, J 18.3), 2.47 (1HA, d, J 17.6), 2.75 (1HB, d, J 15.5), 2.90-2.95 (2HA, m), 3.26 (3HA, s), 3.38-3.41 (2HA+B, m), 3.84 (1HB, d, J 18.3), 3.90 (3HB, s), 6.90 (1HB, m), 7.07 (1HA, m), 7.24-7.35 (12HA+B, m), 7.42 (2HA, m), 7.55 (2HB, d, J 7.7); 13C NMR (CDCl3): δ = 23.7 (1CA), 25.4 (1CB), 32.0 (1CA), 35.5 (1CB), 35.8 (1CB), 36.3 (1CA), 52.4 (1CA), 53.0 (1CB), 58.1 (1CA), 59.4 (1CB), 89.3 (1CB), 89.9 (1CA), 125.0 (4CA+B), 125.1 (1CB, q, J 272.3), 125.9 (1CA, q, J 272.4), 126.0 (2CA+B), 126.7 (2CA+B), 127.1 (2CA+B, q, J 6.0), 128.1 (2CA+B, q, J 6.0), 128.3 (2CA), 128.3 (2CB), 129.1 (1CA), 129.2 (1CB), 129.3 (2CA+B, q, J 32.1), 132.0 (1CB), 132.3 (1CA), 138.9 (1CB), 140.1 (1CA), 172.2 (1CA), 173.0 (1CB), 173.3 (1CB), 173.8 (1CA); 19F NMR (CDCl3): δ = -58.5 (6FA+B); IR: ν = 701, 767, 1001, 1310, 1730, 1784, 2954 cm-1; MS (EI): m/z = 273 (15), 272 (100), 252 (12), 249 (41), 240 (36), 213 (10), 212 (8), 204 (21), 203 (6), 202 (36), 193 (23), 185 (7), 184 (6), 177 (6), 173 (27), 165 (14), 164 (8), 115 (8), 105 (6), 77 (6); HRMS: m/z (ESI) calcd. for C21H19F3O4Na (M+22.9898): 415.11276; found: 415.11255. O
O
ACCEPTED MANUSCRIPT Methyl 3-(4-methoxycarbonylbenzyl)-2-methyl-5-oxo-2-phenyltetrahydrofuran-3-carboxylate 4ag Prepared following general procedure, using acetophenone (0.58 mL, 5 mmol, 1 eq.) and 4methylbromobenzoate (1.60 g, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4agA and 4agB were H 3C obtained in a 35 : 65 ratio as a yellow oil; yield: 0.880 g (46%); Rf: 0.55 (pentane/diethyl ether CO2Me mixture (7:3)); 1H NMR (CDCl3): δ = 1.76 (3HB, s), 1.96 (3HA, s), 2.25 (1HB, d, J 13.7), 2.60-2.69 (2HA+B, m), 2.80-2.93 (3HA+B, m), 3.25-3.30 (4HA, m), 3.73 (1HA, d, J 13.6), 3.80 (3HB, s), 3.87 (3HB, s), 3.88 (3HA, s), 7.01 (2HB, d, J 8.2), 7.19 (2HA, d, J 8.2), 7.25-7.45 (4HA+B, m), 7.37-7.40 (4HA, m), 7.59 (2HB, d, J 7.4), 7.89 (2HB, d, J 8.2), 7.67 (2HA, d, J 8.2); 13C NMR (CDCl3): δ = 23.1 (1CA), 25.3 (1CB), 35.7 (1CB), 35.9 (1CA), 37.7 (1CA), 40.4 (1CB), 52.1 (2CA+B), 52.7 (2CA+B), 58.8 (1CB), 59.8 (1CA), 89.4 (1CB), 89.5 (1CA), 124.6 (2CA), 124.9 (2CB), 126.0 (2CB), 127.2 (2CA), 128.2 (4CA+B), 129.2 (1CA), 129.3 (1CB), 129.8 (4CA+B), 129.9 (1CB), 130.2 (1CA), 139.0 (1CB), 140.1 (1CA), 141.2 (2CA+B), 166.7 (2CA+B), 170.7 (1CA), 171.6 (1CB), 173.6 (1CB), 174.3 (1CA); IR: ν = 702, 764, 950, 1109, 1221, 1280, 1716, 1781, 2953 cm-1; MS (EI): m/z = 351 (11), 281 (6), 263 (17), 262 (100), 247 (7), 235 (13), 234 (91), 230 (28), 207 (28), 203 (30), 202 (19), 192 (21), 175 (17), 174 (17), 171 (10), 143 (17), 131 (7), 121 (7), 115 (16), 91 (8); HRMS: m/z (ESI) calcd. for C22H22O6Na (M+22.9898): 405.13086; found: 405.13120. CO2Me
O
RI PT
O
Methyl 3-benzyl-2-methyl-5-oxo-2-(3,4,5-trimethoxyphenyl)tetrahydrofuran-3-carboxylate 4ah
Prepared following general procedure, using 3,4,5-trimethoxyacetophenone (1.05 g, 5 mmol, 1 eq.) and bromobenzene (0.8 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4ahA and 4ahB were H3 C MeO obtained in a 51 : 49 ratio as a yellow oil ; yield: 2.05 g (99 %); Rf: 0.14 (pentane/diethyl ether CO2 Me mixture (7:3)); 1H NMR (CDCl3): 1.74 (3HB, s), 2.06 (3HA, s), 2.41 (1HA, d, J 13.6), 2.68 (1HA, d, J MeO OMe 17.8), 2.73 (1HB, d, J 17.8), 2.85 (1HA, d, J 13.6), 2.93 (1HB, d, J 17.8), 3.07 (1HB, d, J 13.4), 3.30 (4HA+B, m), 3.63 (1HB, d, J 13.4), 3.75-4.01 (21HA+B, m), 5.37 (4HA+B, s), 6.69 (1HB, s), 6.96 (2HB, m), 7.03 (2HA, m), 7.23-7.25 (5HA+B, m); 13C NMR (CDCl3): 23.7 (1CB), 25.7 (1CA), 36.2 (1CA), 37.9 (1CB), 38.6 (1CB), 40.5 (1CA), 52.3 (1CB), 52.9 (1CA), 56.6 (2CA), 56.7 (2CB), 59.9 (1CA), 60.0 (2CA+B), 61.4 (1CB), 89.6 (1CA), 89.7 (1CB), 104.0 (2CA),105.0 (2CB), 127.8 (1CB), 127.9 (1CA), 129.3 (4CA+B), 130.7 (2CB), 130.9 (2CA), 136.0 (2CA+B), 137.3 (1CA), 137.8 (1CB), 139.0 (2CA+B), 154.0 (2CA), 154.2 (2CB), 170.8 (1CA), 172.4 (1CB), 173.4 (1CA), 174.1 (1CB); IR: ν = 590, 704, 839, 1118, 1219, 1247, 1334, 1418, 1454, 1516, 1592, 1727, 2943 cm-1; MS (EI): m/z = 415 (12), 414 (45), 212 (8), 211 (45), 210 (100), 204 (9), 196 (6), 195 (40), 176 (13), 172 (7), 169 (14), 117 (8), 116 (8), 115 (11), 91 (5); HRMS: m/z (ESI) calcd. for C23H26O7Na (M+22.9898): 437.15707; found: 437.15714. O
M AN U
SC
O
Methyl 3-(4-(methoxybenzyl)-2-methyl-5-oxo-2-(3,4,5-trimethoxyphenyl)tetrahydrofuran-3-carboxylate 4ai Prepared following general procedure, using 3,4,5-trimethoxyacetophenone (1.05 g, 5 mmol, 1 eq.) and 4-bromoanisole (0.9 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4aiA and 4aiB were O H3 C obtained in a 62 : 38 ratio as a yellow oil; yield: 1.972 g (89 %); Rf: 0.20 (pentane/diethyl ether MeO CO2Me mixture (7:3)); 1H NMR (CDCl3): δ = 1.63 (3HA, s), 1.85 (3HB, s), 2.49-2.56 (2HA+B, m), 2.65MeO 2.70 (2HA+B, m), 2.75-2.85 (2HA+B, m), 3.22 (1HA, d, J 18.1), 3.28 (3HB, s), 3.56 (1HB, d, J 13.3), OMe 3.67-3.85 (27HA+B, m), 6.45 (2HB, s), 6.68-6.82 (6HA, m), 6.92-6.95 (2HB, m), 7.15-7.18 (2HB, m); 13C NMR (CDCl3): δ = 23.1 (1CB), 25.9 (1CA), 35.6 (1CA), 35.8 (1CB), 37.2 (1CB), 39.4 (1CA), 52.1 (1CB), 52.5 (1CA), 52.1 (1CA), 52.5 (1CB), 55.2 (2CA+B), 56.3 (4CA+B), 59.1 (2CA+B), 89.3 (1CB), 89.5 (1CA), 102.7 (2CA), 103.6 (2CB), 114.0 (2CA), 114.1 (2CB), 127.4 (2CA+B), 127.5 (2CA+B), 130.8 (2CA), 130.9 (2CB), 134.9 (1CA), 136.2 (1CB), 152.9 (2CA), 153.0 (2CB), 158.8 (2CA+B), 171.2 (1CB), 172.0 (1CA), 173.9 (1CA), 174.7 (1CB); IR: ν = 838, 1123, 1245, 1335, 1416, 1511, 1591, 1697, 2839, 2942 cm-1; MS (EI): m/z = 445 (20), 444 (81), 288 (8), 234 (34), 233 (25), 212 (11), 211 (42), 210 (100), 207 (10), 206 (57), 205 (11), 202 (13), 195 (50), 175 (10), 169 (17), 147 (16), 146 (25), 145 (8), 135 (9), 121 (18); HRMS: m/z (ESI) calcd. for C24H28O8Na (M+22.9898): 467.16764; found: 467.16788. OMe
AC C
EP
TE D
O
Methyl 3-benzyl-2-methyl-5-oxo-2-(3-(trifluoromethyl)phenyl)tetrahydrofuran-3-carboxylate 4aj Prepared following general procedure, using 3-trifluoroacetophenone (0.75 mL, 5 mmol, 1 eq.) and bromobenzene (0.8 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4ajA and 4ajB were obtained in a H3C 45 : 55 ratio as a yellow oil; yield: 1.07 g (51 %); Rf: 0.28 (pentane/diethyl ether mixture (7:3)); 1H F3C CO2Me NMR (CDCl3): δ = 1.77 (3HB, s), 2.01 (3HA, s), 2.23 (1HB, d, J 13.7), 2.69-2.76 (3HA+B, m), 2.862.92 (2HA, m), 3.35 (3HA, s), 3.36 (1HB, d, J 18.1), 3.72 (1HA, d, J 13.2), 3.85 (3HB, s), 6.95 (2HB, d, J 7.5), 7.13 (2HA, d, J 6.4), 7.24-7.31 (6HA+B, m), 7.54-7.68 (6HA+B, m), 7.91 (1HB, d, J 7.8), 7.97 (1HB, s); 13C NMR (CDCl3): δ = 23.1 (1CB), 25.4 (1CA), 35.3 (1CB), 35.8 (1CA), 37.7 (1CA), 40.6 (1CB), 52.1 (1CA), 52.7 (1CB), 58.8 (1CB), 60.1 (1CA), 88.6 (1CB), 88.7 (1CA), 120.0 (1CB, q, J 3.8), 122.1 (1CA, q, J 3.8), 123.1 (1CA, q, J 3.6), 125.1 (1CB, q, J 3.6), 127.4 (2CA+B), 128.4 (2CA+B, q, J 297.7), 128.7 (2CA), 128.8 (2CB), 128.9 (2CA+B), 129.1 (2CA+B), 129.7 (2CB), 129.9 (2CA), 130.9 (2CA+B, q, J 32.2), 135.2 (1CA), 135.5 (1CB), 140.3 (1CB), 141.7 (1CA), 170.7 (1CA), 171.6 (1CB), 173.0 (1CB), 173.7 (1CA); 19F NMR (CDCl3): δ = -62.8 (6FA+B); IR: ν = 702, 806, 1007, 1071, 1167, 1221, 1384, 1714, 1731, 1787, 2954 cm-1; MS (EI): m/z = 392 (6), 373 (8), 342 (10), 332 (6), 313 (6), 205 (9), 204 (78), 203 (37), 177 (19), 176 (100), 175 (9), 173 (24), 172 (66), 145 (41), 144 (39), 134 (23), 117 (55), 116 (68), 115 (48), 91 (26); HRMS: m/z (ESI) calcd. for C21H19F3O4Na (M+22.9898): 415.11276; found: 415.11303. O
O
ACCEPTED MANUSCRIPT Methyl 3-(4-methoxybenzyl)-2-methyl-5-oxo-2-(3-(trifluoromethyl)phenyl)tetrahydrofuran-3-carboxylate 4ak Prepared following general procedure, using 3-trifluoroacetophenone (0.75 mL, 5 mmol, 1 eq.) and 4-bromoanisole (0.9 mL, 7.5 mmol, 1.5 eq.). Both diastereoisomers 4akA and 4akB were H3C obtained in a 44 : 56 ratio as a yellow oil; yield: 1.09 g (52 %); Rf: 0.26 (pentane/diethyl ether F3C CO2Me mixture (7:3)); 1H NMR (CDCl3): δ = 1.70 (3HB, s), 2.10 (4HA+B, m), 2.56-2.84 (4HA+B, m), 3.27 (4HA, m), 3.49-3.61 (2HA+B, m), 3.70 (3HA, s), 3.72 (3HB, s), 3.79 (3HB, s), 6.71-6.81 (6HA+B, m), 6.97 (2HB, m), 7.44-7.84 (8HA+B, m); 13C NMR (CDCl3): δ = 23.1 (1CB), 25.4 (1CA), 35.3 (1CA), 35.8 (1CB), 36.9 (1CA), 39.8 (1CB), 52.0, (2CA+B), 52.8 (1CA), 55.2 (1CB), 58.9 (1CB), 60.2 (1CA), 88.6 (1CB), 88.7 (1CA), 114.1, (4CA+B), 122.0 (1CB, q, J 3.8), 123.1 (1CA, q, J 3.8), 124.6 (1CA, q, J 3.7), 125.1 (1CB, q, J 3.7), 127.0 (1CB), 127.3 (1CA), 128.1 (1CA), 128.3 (1CB), 128.5, (2CA+B, q, J 272.8), 128.7 (1CA), 129.0 (1CB), 129.6 (1CB, q, J 36.9), 130.7 (2CB), 130.9 (2CA), 131.1 (1CA, q, J 36.9 Hz), 140.4 (1CB), 141.8 (1CA), 158.9, (2CA+B), 170.8 (1CA), 171.7 (1CB), 173.1 (1CB), 173.8 (1CA); 19F NMR (CDCl3): δ = -62.8 (6FA+B); IR: ν = 680, 804, 1072, 1119, 1165, 1249, 1331, 1513, 1732, 1786, 2954 cm-1; MS (EI): m/z = 423 (5), 422 (24), 234 (8), 233 (6), 206 (15), 175 (6), 147 (8), 146 (13), 145 (6), 122 (10), 121 (100), 91 (7), 77 (5); HRMS: m/z (ESI) calcd. for C22H21F3O5Na (M+22.9898): 445.12333; found: 445.12363. O
OMe
SC
Methyl 3-benzyl-2,2-dimethyl-5-oxotetrahydrofuran-3-carboxylate 4al
RI PT
O
Prepared following general procedure, using acetone (0.76 mL, 10 mmol, 1 eq.) and bromobenzene (1.9 mL, 15 mmol, 1.5 eq.). Compound 4al was obtained as a colorless solid, mp: 106°C; yield: 1.49 g (66 H3C %); Rf: 0.33 (pentane/diethyl ether mixture (7:3)); 1H NMR (CDCl3): δ = 1.36 (3H, s), 1.64 (3H, s), 2.59 H3C CO2Me (1H, d, J 18.1), 2.65 (1H, d, J 13.4), 3.07 (1H, d, J 18.1), 3.48 (1H, d, J 13.4), 3.75 (3H, s), 7.04 (2H, d, J 8.0), 7.23-7.26 (3H, m); 13C NMR (CDCl3): δ = 22.4 (1C), 24.9 (1C), 35.2 (1C), 38.2 (1C), 52.4 (1C), 57.8 (1C), 86.4 (1C), 127.4 (1C), 128.8 (1C), 129.6 (1C), 135.7 (1C), 171.8 (1C), 173.9 (1C); IR: ν = 794, 1017, 1147, 1204, 1256, 1322, 1437, 1725, 1775, 2954 cm-1; MS (EI): m/z = 263 (7), 262 (25), 247 (34), 231 (14), 230 (100), 205 (6), 204 (53), 203 (53), 202 (39), 201 (8), 187 (8), 186 (5), 185 (9), 184 (14), 177 (7), 176 (50), 175 (12), 172 (19), 171 (6), 159 (7), 157 (15), 156 (7), 145 (31), 144 (29), 143 (18), 134 (12), 117 (44), 116 (47), 115 (43), 92 (6), 91 (65), 65 (8); Anal. calcd. for C15H18O4 (262.12): C 68.68, H 6.92; found: C 68.79, H 6.99. O
M AN U
O
Methyl 4-benzyl-2-oxo-1-oxaspiro[4.5]decane-4-carboxylate 4am
Prepared following general procedure, using cyclohexanone (1.04 mL, 10 mmol, 1 eq.) and bromobenzene (1.9 mL, 15 mmol, 1.5 eq.). Compound 4am was obtained as a colorless oil; yield: 0.42 g (14 %); Rf: 0.37 (pentane/diethyl ether mixture (7:3)); 1H NMR (CDCl3): δ = 1.17-2.12 (10H, m,), 2.59 CO2Me (1H, d, J 18.1), 2.63 (1H, d, J 13.3), 3.07 (1H, d, J 18.1), 3.46 (1H, d, J 13.3), 3.76 (3H, s), 7.05 (2H, d, J 8.0), 7.26-7.27 (3H, m); 13C NMR (CDCl3): δ = 21.8 (1C), 22.3 (1C), 25.0 (1C), 30.3 (1C), 33.1 (1C), 35.2 (1C), 37.7 (1C), 52.3 (1C), 58.4 (1C), 87.7 (1C), 127.3 (1C), 128.7 (1C), 129.8 (1C), 135.8 (1C), 171.1 (1C), 174.1 (1C); IR: ν = 701, 892, 1056, 1066, 1229, 1251, 1394, 1406, 1734, 2361, 2901, 2987 cm-1; MS (EI): m/z = 303 (5), 302 (29), 271 (17), 270 (100), 243 (6), 242 (9), 241 (10), 225 (7), 224 (8), 211 (21), 205 (8), 204 (56), 177 (8), 176 (56), 173 (6), 172 (27), 145 (16), 144 (15), 134 (8), 117 (22), 116 (26), 115 (21), 91 (42), 65 (6); Anal. calcd. for C18H22O4 (302.15): C 71.50, H 7.33; found: C 71.35, H 7.45. O
AC C
EP
TE D
O
ACCEPTED MANUSCRIPT
4.5. Biological evaluations
M AN U
SC
RI PT
The human cell lines were obtained from ATCC, except when otherwise stated and grown in D-MEM or in RPMI medium supplemented with 10% fetal calf serum, in the presence of penicilline, streptomycine and fungizone in 75 cm² flask under 5% CO2 at 37°C. Cells were plated in 96-well tissue culture plates in 200µl medium and treated 24 h later with 2 µl stock solution of compounds 4a-am dissolved in DMSO using a Biomek 3000 (BeckmanCoulter) in sterile conditions. Controls received the same volume of DMSO (1% final volume). After 72 h exposure, MTS reagent (Promega) was added and incubated for 3 h at 37°C: the absorbance was monitored at 490 nm and results expressed as the inhibition of cell proliferation calculated as the ratio [(1-(OD490 treated/OD490 control))×100] in triplicate experiments [44]. Necrosis was estimated through the release of LDH from HL60 cells in the culture medium. 25 µL of culture medium was added with 25 µL Cytotox-ONE reagent (Promega) and kept in the dark at room temperature for 20 min. Fluorescence was recorded (exc 560 nm, em 590 nm) and results are expressed as the residual activity in the presence of chemicals compared to activity in the presence of vehicle alone. Apoptotic and necrotic cells were analyzed in flow cytometry using HL60 cells. Double-staining for phosphatidyl serine and DNA was performed by addition of staining solution containing annexin V-PE (Bender MedSystems) and 7-AAD (Enzo Biomol). Cellular fluorescence was measured by flow cytometry with a Guava EasyCyte plus cytometer (Millipore). HL60 cells were exposed to compounds for 24 and 48 h at 37°C under 5% CO2. Cells were stained with propidium iodide before be analyzed by flow cytometry with a Guava Easycyte cytometer (Millipore). Cell populations were quantified using Modfit LT (Verity Software House). Caspase activities were assayed in HL60 cell after a 48 h treatment. Cell lysates were added with DEVD-AMC, incubated at 37°C and fluorescence was recorded (exc 360 nm, em 435 nm). Results are expressed as the fold-activation relative to the control. Acknowledgments
Financial support of this work by the CNRS and the University Paris-Est (PhD grant) is gratefully acknowledged.
[2] [3]
H. M. R. Hoffmann, J. Rabe, Synthesis and Biological Activity of α-Methylene-γ-butyrolactones, Angew. Chem. Int. Ed. 24 (1985) 94-110. N. H. Fischer, T. Lu, C. L. Cantrell, J. Castaneda-Acosta, L. Quijano, S. Franzblau, Antomycobacterial Evaluation of Germacranolides, Phytochemistry 49 (1998) 559-564. T.-C. Wang, K.-H. Lee, Y.-L. Chen, S.-S. Liou, C.-C. Tzeng, Synthesis and Anticancer Evaluation of certain γ-aryloxymethyl-α-methylene-γ-phenyl-γ-butyrolactones, Bioorg. Med. Chem. Lett. 8 (1998) 2773-2776.
EP
[1]
TE D
References and notes
Y. Higuchi, F. Shimoma, M. Ando, Synthetic Method and Biological Activities of cis-Fused α-Methylene γLactones, J. Nat. Prod. 66 (2003) 810-817.
[5]
M. A. Hughes, J. M. McFadden, C. A. Townsend, New α-methylene-γ-butyrolactones with antimycobacterial properties, Bioorg. Med. Chem. Lett. 15 (2005) 3857–3859.
[6]
N. Petragnani, H. M. C. Ferraz, G. V. J. Silva, Advances in the Synthesis of α-Methylenelactones, Synthesis (1986) 157-183. M. Pohmakotr, W. Harnying, P. Tuchinda, V. Reutrakul, Vicinal Dianion of Triethyl Ethanetricarboxylate:
[7]
AC C
[4]
Syntheses of (±)-Lichesterinic Acid, (±)-Phaseolinic Acid, (±)-Nephromopsinic Acid, (±)-Rocellaric Acid and [8]
(±)-Dihydroprotolichesterinic Acid, Helv. Chim. Acta 85 (2002) 3792-3813. D. Blanc, J. Madec, F. Popowyck, T. Ayad, P. Phansavath, V. Ratovelomanana, J.-P. Genêt, General Enantioselective Synthesis of Butyrolactone Natural Products via Ruthenium-SYNPHOS-Catalyzed Hydrogenation Reactions, Adv. Synth. Catal. 349 (2007) 943-950.
[12] [13]
[14] [15] [16]
[17] [18] [19]
synthesis of diastereoisomeric ethyl γ-benzyl paraconates and determination of the absolute configuration of their acids, Tetrahedron: Asymmetry 17 (2006) 2344–2353. A. M. Jacobine, W. Lin, B. Walls, C. K. Zercher, Formation of γ-Lactones through CAN-Mediated Oxidative Cleavage of Hemiketals, J. Org. Chem. 73 (2008) 7409-7412. Y. Li, Z.-A. Zhao, H. He, S.-L. You, Stereoselective Synthesis of γ-Butyrolactones via Organocatalytic Annulations of Enals and Keto Esters Adv. Synth. Catal. 350 (2008) 1885–1890. S. N. Greszler, J. S. Johnson, Diastereoselective Synthesis of Pentasubstituted γ-Butyrolactones from Silyl Glyoxylates and Ketones through a Double Reformatsky Reaction Angew. Chem. Int. Ed. 48 (2009) 3689– 3691. T. Shono, H. Hamaguchi, I. Nishiguchi, M. Sasaki, T. Miyamoto, M. Miyamoto, S. Fujita, New Zinc Promoted
TE D
[20]
RI PT
[11]
SC
[10]
S. Bazin, L. Feray, N. Vanthuyne, D. Siri, M. P. Bertrand, α-β-Unsaturated diesters: radical acceptors in ACCEPTED MANUSCRIPT dialkylzinc-mediated tandem radical addition/aldol condensation. A straightforward synthesis of racnephrosteranic acid, Tetrahedron 63 (2007) 77-85. H.-C. Kim, O.-S. Park, Efficient stereoselective synthesis of enantiopure 2-substituted paraconic acids, Tetrahedron: Asymmetry 19 (2008) 896–899. M. Amador, X. Ariza, J. Garcia, J. Ortiz, A Straightforward Synthesis of (-)-Phaseolinic Acid, J. Org. Chem 69 (2004) 8172-8175. For a recent review on the synthesis of paraconic acids, see: R. Bandichhor, B. Nosse, O. Reiser, Paraconic Acid-The Natural products from Lychen Symbiont, O. Top. Curr. Chem. 243 (2005) 43-72. M. M. Murta, M. B. M. De Azevedo, A. E. Greene, Synthesis and Absolute Stereochemistry of (-)Protolichesterinic Acid, Antitumor Antibiotic Lactone from Cetraria Islandica, J. Org. Chem. 58 (1993) 75377541. C. Böhm, O. Reiser, Enantioselective Synthesis of (-)-Roccellaric Acid, Org. Lett. 3 (2001) 1315-1318. K. Müller, Pharmaceutically relevant metabolites from lichens, Appl. Microbiol. Biotechnol. 56 (2001) 9-16. F. Berti, F. Felluga, C. Forzato, G. Furlan, P. Nitti, G. Pitacco, E. Valentin, M. T. Barros, Chemoenzymatic
M AN U
[9]
Synthetic Reaction of γ-Butyrolactones Derivatives, Chem. Lett. (1981) 1217-1220. [21] F. D’Onofrio, R. Margarita, L. Parlanti, G. Piancatelli, M. Sbraga, Tandem Michael-aldol induced ring closure of dimethyl-2-phenylselenofumarate: a diastereoselective entry to novel 4-phenylselenobutano-4-lactone derivatives, versatile precursors of naturally occurring compounds, Chem. Commun. (1998) 185-186.
EP
[22] A. Méou, L. Lamarque, P. Brun, Efficient MnIII-mediated synthesis of functionalized trans-3,4-disubstituted γbutyrolactones, Tetrahedron Lett. (43) 2002 5301-5304.
AC C
[23] The synthesis of monosubstituted lactones (N-Carbamoylmethyl-α-aminobutyrolactones) by the Ugi multicomponent reaction has been reported, see: S. J. Park, G. Keum, S. B. Kang, H. Y. Koh, Y. Kim, A facile synthesis of N-carbamoylmethyl- α -aminobutyrolactones by the Ugi multicomponent condensation reaction, Tetrahedron Lett. 39 (1998) 7109-7112. [24] For the synthesis of α-methylene-γ-butyrolactones starting from preformed alkylcopper reagents, Michael
[25] [26] [27] [28]
acceptors and aldehydes, see: A. Sidduri P. Knochel, New preparation of α-methylene-γ-butyrolactones mediated by (iodomethyl)zinc iodide, J. Am. Chem. Soc. 114 (1992) 7579–7581. J. Zhu, H. Bienaymé, Multicomponent Reactions, Wiley-VCH, Weinheim, 2005. R. V. A. Orru, M. De Greef, Recent Advances in Solution-Phase Multicomponent Methodology for the Synthesis of Heterocyclic Compounds, Synthesis (2003) 1471-1499. J. Zhu, Recent Developments in the Isonitrile-Based Multicomponent Synthesis of Heterocycles, Eur. J. Org. Chem. (2003) 1133-1144. C. Simon, T. Constantieux, J. Rodriguez, Utilisation of 1,3-Dicarbonyl Derivatives in Multicomponent Reactions, Eur. J. Org. Chem. (2004) 4957-4980.
[29] A. Dömling, Recent Developments in IsocyanideMANUSCRIPT Based Multicomponent Reactions in Applied Chemistry, ACCEPTED Chem. Rev. 106 (2006) 17-89. [30] D. M. D’Souza, T. J. J. Müller, Multi-component syntheses of heterocycles by transition-metal catalysis, Chem. Soc. Rev. 36 (2007) 1095-1108. [31] G. Guillena, D. J. Ramón, M. Yus, Organocatalytic enantioselective multicomponent reactions (OEMCRs), Tetrahedron: Asymmetry 18 (2007) 693-700.
RI PT
[32] The synthesis of monosubstituted lactones (N-Carbamoylmethyl-α-aminobutyrolactones) by the Ugi multicomponent reaction has been reported, see: S. J. Park, G. Keum, S. B. Kang, H. Y. Koh, Y. Kim, A facile synthesis of N-carbamoylmethyl- α -aminobutyrolactones by the Ugi multicomponent condensation reaction, Tetrahedron Lett. 39 (1998) 7109-7112. [33] For the synthesis of α-methylene-γ-butyrolactones starting from preformed alkylcopper reagents, Michael acceptors and aldehydes, see: A. Sidduri P. Knochel, New preparation of α-methylene-γ-butyrolactones mediated by (iodomethyl)zinc iodide, J. Am. Chem. Soc. 114 (1992) 7579–7581.
[41] [42]
[43]
[44]
TE D
[40]
EP
[38] [39]
Approach to Novel 2,3-Di and 2,2,3-Trisubstituted-3-methoxycarbonyl-γ-Butyrolactones, Eur. J. Org. Chem. (2010) 5279-5286. H. Fillon, C. Gosmini, J. Périchon, New Chemical Synthesis of Functionalized Arylzinc Compounds from Aromatic or Thienyl Bromides under Mild Conditions Using a Simple Cobalt Catalyst and Zinc Dust, J. Am. Chem. Soc. 125 (2003) 3867-3870. Reactions were monitored by Gas Chromatography using an internal standard. R.W. Wang, L.I. Rebhum, S.M. Kupcham. Antimitotic and antitubulin activity of the tumor inhibitor staganacin. Cancer Res. 37 (1977) 3071-3079. For some representative reviews on combretastatins and analogues, see: (a) A. Cirla, J. Mann, Combretastatins: from natural products to drug discovery, Nat. Prod. Rep. 20 (2003) 558–564; (b) H. P. Hsieh, J. P. Liou, N. Mahindroo, Pharmaceutical design of antimitotic agents based on combretastatins, Curr. Pharm. Des. 11 (2005) 1655-1677. X. Liu, H. Zou, C. Slaughter, X. Wang. DFF, a Heterodimeric Protein That Functions Downstream of Caspase3 to Trigger DNA Fragmentation during Apoptosis. Cell 89 (1997) 175-184. G. Loor, J. Kondapalli, J.M. Schriewer, N.S. Chandel, T.L. Vanden Hoek, P.T. Schumacker. Menadione triggers cell death through ROS-dependent mechanisms involving PARP activation without requiring apoptosis. Free Radic. Biol. Med. 49 (2010) 1925-1936. DW. Nicholson, A. Ali, N.A. Thornberry, J.P. Vaillancourt, C.K. Ding, M. Gallant, Y. Gareau, P.R. Griffin, M. Labelle, Y.A. Lazebnik, N.A. Munday, S.M. Raju, M.E. Smulson, T.T. Yamin, V.L. Yu, D.K. Miller. Identification and inhibition of the ICE/CED-3 protease necessary for mammalian apoptosis. Nature 376 (1995) 37-43. L. Eloy, A.S. Jarrousse, M.L. Teyssot, A. Gautier, L. Morel, C. Jolivalt, T. Cresteil, S. Roland. Anticancer Activity of Silver(I)–N-Heterocyclic Carbenes: Caspase-independent Induction of Apoptosis via the Mitochondrial Apoptosis Inducing Factor (AIF), ChemMedChem 7 (2012) 805-814.
AC C
[37]
M AN U
SC
[34] E. Le Gall, C. Haurena, S. Sengmany, T. Martens, M. Troupel, Three-Component Synthesis of α-Branched Amines under Barbier-like conditions, J. Org. Chem. 74 (2009) 7970-7973. [35] C. Le Floch, E. Le Gall, E. Léonel, T. Martens, T. Cresteil, Synthesis and cytotoxic evaluation of novel paraconic acid analogs, Bioorg. Med. Chem. Lett. 21 (2011) 7054-7058. [36] C. Le Floch, E. Le Gall, E. Léonel, J. Koubaa, T. Martens, P. Retailleau, A Cobalt-Catalyzed Multicomponent
