Bioorganic & Medicinal Chemistry 22 (2014) 3922–3930

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Synthesis and fungicidal activity of quinolin-6-yloxyacetamides, a novel class of tubulin polymerization inhibitors Clemens Lamberth a,⇑, Fiona Murphy Kessabi a, Renaud Beaudegnies a, Laura Quaranta a, Stephan Trah a, Guillaume Berthon a, Fredrik Cederbaum a, Gertrud Knauf-Beiter b, Valeria Grasso b, Stephane Bieri b, Andy Corran c, Urvashi Thacker c a b c

Syngenta Crop Protection AG, Research Chemistry, Schaffhauserstr. 101, CH-4332 Stein, Switzerland Syngenta Crop Protection AG, Research Biology, Schaffhauserstr. 101, CH-4332 Stein, Switzerland Syngenta Ltd, Jealott’s Hill International Research Centre, Bracknell, Berkshire RG42 6EY, United Kingdom

a r t i c l e

i n f o

Article history: Received 7 April 2014 Revised 3 June 2014 Accepted 6 June 2014 Available online 17 June 2014 Keywords: Tubulin Quinoline Heterocycle Fungicide Crop protection

a b s t r a c t A novel class of experimental fungicides has been discovered, which consists of special quinolin-6-yloxyacetamides. They are highly active against important phytopathogens, such as Phytophthora infestans (potato and tomato late blight), Mycosphaerella graminicola (wheat leaf blotch) and Uncinula necator (grape powdery mildew). Their fungicidal activity is due to their ability to inhibit fungal tubulin polymerization, leading to microtubule destabilization. An efficient synthesis route has been worked out, which allows the diverse substitution of four identified key positions across the molecular scaffold. Ó 2014 Elsevier Ltd. All rights reserved.

1. Introduction Microtubules are hollow cylindrical tubes found in all eukaryotic cell types. These essential cytoskeletal protein polymers play a pivotal role in maintaining the growth, shape, division, motility and functioning of the cell. Microtubules are key components of the mitotic spindle, which enables the segregation of chromosomes during the process of mitosis. They are built by polymerization of the two globular protein subunits a- and b-tubulin, which first combine to a,b-heterodimers. Interference with the microtubule homeostasis by disrupting the dynamic equilibrium between the depolymerization of microtubules into tubulin or, inversely, the assembly of tubulin into microtubules leads to arrested cell division and consequently to apoptosis.1 Especially this latter possibility, the inhibition of the tubulin polymerization, also called microtubule destabilization, has widely impacted the chemotherapeutic treatment of human cancer diseases2 as well as the protection of plants against fungal diseases.3 A group of special natural products, such as the vinca alkaloids,4 for example vinblastine,5 vincristine,6 vinorelbine7 and vindesine,8 but also colchicine9 and

⇑ Corresponding author. Tel.: +41 62 866 0224; fax: +41 62 866 0860. E-mail address: [email protected] (C. Lamberth). http://dx.doi.org/10.1016/j.bmc.2014.06.015 0968-0896/Ó 2014 Elsevier Ltd. All rights reserved.

combretastatin10 are a well-established class of anti-cancer agents. On the other hand tubulin polymerization inhibitors such as the methyl benzimidazole carbamates (MBC’s),11 for example benomyl,12 carbendazim,13 thiabendazole14 and fuberidazole,15 are successfully applied as agrochemical fungicides. Although much effort is currently put into the search for novel tubulin polymerization inhibitors, there is clearly a lack of additional, independent subclasses. In oncology, many of the identified active compounds depend on scaffolds based on the well-known 3,4,5-trimethoxyphenyl ring of colchicine and combretastatin.16–25 In crop protection, the introduction of the MBC’s as very first systemic active fungicide class in the 1960s revolutionized the agrochemical market, but in the following decades with zoxamide26 and ethaboxam27 only two further tubulin polymerization inhibitors have been developed. Therefore there is definitely a need for active ingredients with completely novel structural entities. In this paper we present quinolin-6-yloxyacetamides as a novel class of tubulin polymerization inhibitors.28–30 Their discovery was clearly fertilized by cross-indication screening, because the glyoxylic acid acetal derivative 1, belonging to a herbicide project, was identified as a fungicide hit owing to some weak, but interesting signals in the greenhouse (Fig. 1). The thorough optimization of this lead compound led to quinolin-6-yloxyacetamides such as 2, which shows powerful fungicidal activity in field trials.

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C. Lamberth et al. / Bioorg. Med. Chem. 22 (2014) 3922–3930 O

O O

Cl

O

N H

O

S

N

N H

N

O

Cl 1

2

initial lead structure from herbicide project

typical example of fungicidally active quinolin-6-yloxyacetamides

Figure 1. Typical quinolin-6-yloxyacetamide 2 and its original lead compound 1.

2. Results and discussion 2.1. Chemistry 3-Bromo-8-methylquinolin-6-ol (7) is a key building block in the synthesis of the fungicidally active quinolin-6-yloxyacetamides 9 and 12 (Scheme 1). We have recently described the efficient twostep preparation of this compound via Skraup-type cyclization from either 2-methyl-4-nitroaniline (3) or 4-methoxy-2-methylaniline (5) with 2,2,3-tribromopropanal.31 The hydroxyl function in position 6 of the trisubstituted quinoline 7 can be easily alkylated with a-halocarboxylates, for example, leading to the quinolin-6-yloxyacetates 8 and 10 bearing either an ethyl or a thiomethyl group at the a-carbon atom of the ester. These two functionalities played the biggest role during our optimization, but also several further substituents have been introduced by choice of the appropriate a-chlorocarboxylate (Table 4). It is noteworthy, that within this alkylation reaction, completely different functional groups can be produced under the same reaction conditions, as the hydroxyl function of 7 has been transformed into an ether (?8) as well as into a O,S-acetal (?10). The saponification of the ester function in 8 and 10 to the corresponding carboxylic acids and their further conversion with tert-butylamine and propargylamine, respectively, under peptide coupling conditions finally led to the fungicidally active amides 9 and 12. The methyl ester 10, which is a key intermediate in the synthesis of the fungicidally active amide 12, is perfectly suited for the transformation into derivatives with a different quinoline substitution pattern by exchange of the bromine atom. During our optimization of this compound class it turned out that quinolin-6-yloxyacetamides with a carbon-linked substituent in position 3 have been especially interesting. Scheme 2 describes the palladium-catalyzed replacement of the bromo function by four different carbon substituents, an alkyl, an alkenyl, an alkynyl and a cycloalkyl group. The vinyl derivative 13, which can be converted into the final product

CH2 BrCBr2CHO AcOH

NO2

77 %

H2N

NO2

Br

14, is obtained from bromoquinoline 10 by a palladium-catalyzed Stille reaction with vinyltributyltin.32 Another possibility for the synthesis of 13 is the Sonogashira coupling of trimethylsilylacetylene33 and 10 to the 3-ethynylquinoline 15 and the subsequent partial reduction of the C–C triple bond by catalytic hydrogenation with Lindlar catalyst. In addition, the ester 15 can also converted into the fungicidally active amide 2. The 3-methylquinolin-6-yloxy acetate 16, which delivers the corresponding amide 17, is obtained by Suzuki–Miyaura coupling with trimethylboroxine.34 Finally, the replacement of the bromo substituent of 10 by cyclopropyl was achieved by Suzuki–Miyaura coupling with cyclopropylboronic acid,35 leading to the ester 18 which delivers the target compound 19 upon amidation. These transformations confirm the huge scope of palladium-catalyzed cross-coupling reactions of halogenated quinolines, a field which has been reviewed recently.36 2.2. Mode of action The quinolin-6-yloxyacetamides 2 and 12 were submitted to a polymerization assay on pure porcine tubulin to check if these experimental fungicides are disrupters of the microtubule dynamics. They were compared against colchicine, which is a known tubulin polymerization inhibitor and for which a strong effect on the OD340 value could be detected at 4 lg ml1. Also the two quinolin-6-yloxyacetamides 2 and 12 showed in two different replicates an inhibitory effect on the microtubule formation, which was clearly different from the solvent control (Fig. 2). 2.3. Structure–activity relationships During our derivatisation of this novel class of tubulin polymerization inhibitors we identified four key positions in the molecular scaffold of quinolin-6-yloxyacetamides, which have to bear the right substituents for optimum fungicidal activity. Tables 1–5 describe the effect of replacement of the quinoline core by other rings and of those four important quinoline substituents on the efficacy against the Oomycetes disease Phytophthora infestans (potato and tomato late blight) as well as against Mycosphaerella graminicola (wheat leaf blotch) and Uncinula necator (grape powdery mildew) which are both from the family of Ascomycetes. 2.3.1. Influence of the cyclic core on the fungicidal activity One of the most important breakthroughs during our derivatisation was the discovery, that the 3-bromoquinolin-6-yl scaffold (Table 1, entry 3) is a big improvement compared to the dihalogenated benzene ring of the initial lead compound 1 (entry 1). Conse-

1. Fe, HCl 2. H3PO4, H2O 67 %

N

OH

Br

4

BrCH(Et)CO2Me, K2CO3

3 O CH3

45 %

H2N

91 %

N

CH2 BrCBr2CHO Br AcOH

O CH3

8

ClCH(SMe)CO2Me, 71 % K CO 2 3

6 5 O O

Br N 12

S

N H

67 %

O N 11

OH S

43 % over 1. LiOH two steps 2. HOAt, EDCI, NEt3, HC CCH2NH2

O

O

HOAt, EDCI, tBuNH2,NEt3 Br

O

NaOH Br 100 %

N

O

N

7

HBr 84 %

N

O O

Br

O O

S

10

Scheme 1. Synthesis of the fungicidally active quinolin-6-yloxy acetamides 9 and 12.

O

Br N 9

N H

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O

O

O O

MeOCH2C(Me)(CN)NH2

S

N

N

1. NaOH 2. HOAt, TBTU, NEt3

O

49 % over two steps

13

S

N

O N H

O

O N

14

N H

S

O

17

H2C=CHSnBu3,

61 %

1. HC CSiMe3 PdCl2(PPh3)2, CuI, iPr2NH 2. K2CO3

O O

O S

N

54 % over two steps

15 56 % over two steps

82 % over 1. NaOH two steps 2. HOAt, TBTU, NEt3, MeOCH2C CC(Me)2NH2

Pd(PPh3)4

47 %

H2, Pd/Lindlar quinoline

O O

Br

O S

N 10

2

S

O N H

N

O S

N 16

O

N

51 %

O O

c-PrB(OH)2, 25 % Pd(PPh3)4 K3PO4

1. NaOH 2. HOAt, EDCI, NEt3, MeON=CHC(Me)2NH2

O

(MeBO)3, Pd(PPh3)4 K2CO3

O

O N 18

O S

1. NaOH 2. HOAt, EDCI, NEt3 H2C=C(Cl)CH2NH2 56 % over two steps

O O N

S

N H

Cl

19

Scheme 2. Transformation of the 3-bromoquinoline derivative 10 into different 3-carba-substituted quinolin-6-yloxyacetamides.

at least equal results than bromo and iodo is the ethynyl group (entry 8). This is rather surprising, as the other C2 groups with reduced degree of unsaturation, ethyl (entry 6) and vinyl (entry 7) show clearly weaker fungicidal potency. Also methoxy (entry 10) cannot compete with bromo, iodo and ethynyl. Most of these carbon- and oxygen-linked substituents have been introduced by derivatization of the 3-bromoquinoline building block 10 (Scheme 2).

Figure 2. Degree of polymerization of pure porcine tubulin in the presence of colchicine (4 lg ml1), 2 (1 lg ml1) and 12 (3 lg ml1) in function of time (values presented are a mean of two replicates).

quently, much effort was invested in the fine-tuning of this successful heterobicyclic core. However, shifting the ring nitrogen to the other ring (entry 4), replacing it by a carbon atom (entry 5) or adding a second ring nitrogen to the bicycle (entry 6) clearly decreased the fungicidal potency. Also the replacement of the bromoquinoline of entry 3 by a bromobenzothiophene (entry 7) did not result in sufficient biological activity. 2.3.2. Influence of the substituent in quinoline position 3 on the fungicidal activity The excellent results of several differently 3-substituted quinolines in Table 2 demonstrate the huge scope of variability in this position. Relatively soon after the discovery of the quinoline scaffold we identified the higher halogens bromine (entry 3) and iodine (entry 4) as highly active substituents in this position. The corresponding chloro (entry 2) derivative fails completely against Phytophthora infestans. The only other substituent which delivers

2.3.3. Influence of the substituent on quinoline position 8 on the fungicidal activity Ring carbon 8 is the third quinoline ring position, which was identified besides positions 3 and 6 as crucial to be substituted with the optimum functional group for delivery of the best possible fungicidal activity (Table 3). The substituent in this position could be broadly varied by choice of the appropriate aniline starting material as shown in Scheme 1.28 It seems that a methyl group in this position (entry 6) delivers the highest fungicidal activity, followed by the 8-unsubstituted analog (entry 1) and the chlorinated (entry 3) and brominated (entry 4) derivatives. Interestingly 8-iodo substituted quinolin-6-yloxyacetamide (entry 5) is clearly weaker than its bromo analog (entry 4), whereas in ring position 3 (Table 2), iodo was more or less equal to bromo. Much effort has been undertaken to increase the fungicidal potential of the 8methyl substituted compounds by small structural modifications. However, the elongation of the methyl group to the next higher homolog ethyl (entry 7) as well as the replacement of hydrogen atoms of the methyl group by fluorine atoms (entries 8 and 9) led to a clear drop in fungicidal activity. 2.3.4. Influence of the substituent in the acetic acid moiety on the fungicidal activity The completely missing fungicidal activity of a-unsubstituted quinolin-6-yloxyacetamides (entry 1) demonstrates already the importance of the right substituent in this position of the acetic acid moiety (Table 4). In our experience, two-atom side chains, especially the ethyl group (entry 2) and the methylthio group (entry 6) deliver the best results. Already small modifications lead

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C. Lamberth et al. / Bioorg. Med. Chem. 22 (2014) 3922–3930 Table 1 Influence of the cyclic core on the fungicidal activitya

Entry

R

Phytophthora infestans (potato and tomato late blight)

Table 3 Influence of the substituent in quinoline position 8 on the fungicidal activitya

Mycosphaerella graminicola (wheat leaf blotch)

Uncinula necator (grape powdery mildew)

1

67

15

30

2

13

0

0

3

95

95

100

4

47

0

0

5

10

0

88

6

8

0

0

7

57

0

59

a

a

R

Phytophthora infestans (potato and tomato late blight)

Mycosphaerella graminicola (wheat leaf blotch)

Uncinula necator (grape powdery mildew)

1 2 3 4 5 6 7 8 9 10 11 12

H F Cl Br I CH3 CH2CH3 CHF2 CF3 CN C„CH SCH3

95 83 96 90 0 100 20 0 8 3 80 0

95 87 93 100 79 100 82 100 0 93 98 0

100 100 100 100 3 100 95 28 0 98 100 0

Results are given in % activity at 60 ppm.

Table 4 Influence of the substituent in the acetic acid moiety on the fungicidal activitya

Entry

R1

R2

Phytophthora infestans (potato and tomato late blight)

Mycosphaerella graminicola (wheat leaf blotch)

Uncinula necator (grape powdery mildew)

1 2 3 4 5 6 7 8 9 10 11 12

H CH2CH3 CH2CH2F OCH3 OCH2CH2OCH3 SCH3 SCH2CH3 SPh Pyrazol-1-yl CH2CH3 SCH3 –CH2CH2–

H H H H H H H H H F CH3

0 87 61 0 46 95 14 1 60 0 0 1

0 90 0 74 11 95 0 0 17 4 14 0

0 100 100 100 0 100 9 0 90 0 0 0

Results are given in % activity at 60 ppm.

Table 2 Influence of the substituent in quinoline position 3 on the fungicidal activitya

a

Entry

Entry

R

Phytophthora infestans (potato and tomato late blight)

Mycosphaerella graminicola (wheat leaf blotch)

Uncinula necator (grape powdery mildew)

1 2 3 4 5 6 7 8 9 10

H Cl Br I CH3 CH2CH3 CH@CH2 C„CH C„CCH3 OCH3

97 0 100 99 75 63 65 100 0 13

100 94 100 100 80 90 25 100 0 75

75 100 100 100 100 99 16 100 76 100

Results are given in % activity at 60 ppm.

to dramatic differences in the fungicidal activity, for example the replacement of the sulfur atom in the methylthio group by oxygen (entry 4) and the elongation of the methylthio group by one additional carbon atom (entry 7). The attempt to enhance the activity of the two best substituents ethyl and methylthio by introduction of an additional substituent, leading to a quarternization of the a-acetic acid carbon was not successful at all (entries 10 and

a

Results are given in % activity at 60 ppm.

11). Also another quarternary derivative, in which the a-carbon is part of a cyclopropyl ring, was devoid of any fungicidal activity (entry 12). 2.3.5. Influence of the amine moiety on the fungicidal activity The abundant availability of amines enabled us to check the full scope of this terminal functional group of our quinolin-6-yloxyacetamides. Table 5 compares different primary, secondary and tertiary amides of the same acid building block. Hereby some interesting trends became visible. A NH2 group linked to the acid (primary amide, entry 1) is devoid of any useful fungicidal activity. The best results regarding level of activity and broadness of spectrum have been achieved with the secondary amides (entries 7– 9), in which the quarternary carbon atom next to the amine nitrogen is substituted by either three methyl groups (entry 7), two methyl groups and another carbon substituent (entry 8) or one

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Table 5 Influence of the amine moiety on the fungicidal activitya

a

Entry

R1

R2

Phytophthora infestans (potato and tomato late blight)

Mycosphaerella graminicola (wheat leaf blotch)

Uncinula necator (grape powdery mildew)

1 2 3 4 5 6 7 8 9 10 11 12

H CH2CH(CH3)2 CH2CH@CH2 CH2C(CH3)@CH2 CH(CH3)CH2CH3 CH(CH3)CH2CF3 C(CH3)3 C(CH3)2C„CH C(CH3)(CN)CH2OCH3 C(CH3)2(4-ClPh) C(CH3)3 AC(@O)OCH2C(Me)2-

H H H H H H H H H H CH3

0 0 0 0 0 11 100 100 100 21 1 11

46 80 90 90 80 99 100 100 100 0 72 0

0 100 100 100 98 98 100 100 100 10 76 63

Results are given in % activity at 60 ppm.

methyl group and two other carbon functional groups (entry 9). This impressive level of activity drops immediately, if one of these three carbon substituents at the a-amine carbon exceeds a certain size, such as the p-chlorophenyl ring in entry 10. Also the introduction of a second alkyl group into the amide nitrogen (tertiary amide, entry 11) or the incorporation of the amide nitrogen into an oxazolidinone ring (entry 12) decreased the fungicidal activity. The fact that in general, secondary amides with a CH2 group (entries 2–4) or a CH(Me) group (entries 5 and 6) next to the amine nitrogen selectively lost the activity against the Oomycetes pathogen P. infestans, but kept a high level of efficacy against the Ascomycetes diseases M. graminicola and U. necator was a fascinating discovery. 3. Conclusions Novel quinolin-6-yloxyacetamides have been discovered as a new class of fungicidally active compounds, which are able to control economically important plant diseases, such as P. infestans, M. graminicola and U. necator. Their mode of action is the inhibition of tubulin polymerization, leading to microtubule destabilization. They can be prepared starting from different 4-methoxy- or 4nitroanilines, which deliver in a Skraup-type transformation with 2,2,3-tribromopropanal 3-bromoquinolin-6-ols. These key intermediates can be converted in only few steps into a high number of quinolin-6-yloxyacetamides with different substituents in the quinoline core, the acetic acid part and the amine moiety. A structure–activity relationship study revealed the molecular requirements for the best fungicidal activity. We first discovered the superiority of the quinoline scaffold compared to several other mono- and bicyclic analogs and then identified four key positions which have to be specifically substituted to reach optimum efficacy. Bromo, iodo and ethynyl are by far the best substituents in quinoline position 3, whereas the ring position 8 should bear a hydrogen atom or a methyl group for optimum results and an ethyl or methylthio group linked to the a-carbon atom of the acetic acid moiety. This means, that completely different substituents are required in these three positions for the best fungicidal activity. Furthermore the amine side chain plays an important role for the fungicidal activity. The highest level of activity was achieved by secondary amides, in which the amino function is linked to a quarternary carbon atom. Interestingly, the activity against Oomycetes

diseases, such as P. infestans, can be completely surppressed, when the a-carbon atom of the amine is unsubstituted. 4. Experimental section 4.1. Chemistry All new compounds were characterized by standard spectroscopical methods. 1H NMR spectra were recorded on a Varian Unity 400 spectrometer at 400 MHz using CDCl3 as solvent and tetramethylsilane as internal standard. Chemical shifts are reported in ppm downfield from the standard (d = 0.00), coupling constants in Hz. LC-MS spectra were determined using the following apparatus: ACQUITY UPLC from Waters, Phenomenex Gemini C18, 3 mm particle size, 110 Angström, 30  3 mm column, 1.7 ml/min, 60 °C, H2O + 0.05% HCOOH (95%)/CH3CN/MeOH 4:1 + 0.04% HCOOH (5%)—2 min—CH3CN/MeOH 4:1 + 0.04% HCOOH (5%)—0.8 min; ACQUITY SQD Mass Spectrometer from Waters, ionization method: electrospray (ESI), Polarity: positive ions, Capillary (kV) 3.00, Cone (V) 20.00, Extractor (V) 3.00, Source Temperature (°C) 150, Desolvation Temperature (°C) 400, Cone Gas Flow (L/Hr) 60, Desolvation Gas Flow (L/Hr) 700. Analytical thin-layer chromatography (TLC) was performed using silica gel 60 F524 precoated plates. Preparative flash chromatography was performed using silica gel 60 (40–63 lm, E. Merck). Unless otherwise stated, all reactions were carried out under anhydrous conditions in an inert atmosphere (nitrogen or argon) with dry solvents. 4.1.1. 3-Bromo-8-methyl-6-nitroquinoline(4) 2,2,3-Tribromopropanal28 (29.4 g, 0.1 mol) was slowly added to a suspension of 2-methyl-4-nitroaniline (3, 15,2 g, 0.1 mol) in 200 ml of glacial acetic acid. The reaction mixture was heated to 110 °C for 1 h, then cooled to room temperature and filtered. The remaining solid was washed with diethyl ether, then suspended in water and treated with a saturated aqueous sodium bicarbonate solution until pH 9 was reached. The suspension was transferred to a separatory funnel and extracted with ethyl acetate, the organic phase was dried over magnesium sulfate and evaporated under reduced pressure. The residue was purified by chromatography on silica gel, using ethyl acetate and heptane as eluents to obtain 3-bromo-8-methyl-6-nitroquinoline (4, 20.7 g, 77 mmol, 77%). 1H NMR (CDCl3): d = 2.86 (s, 3H), 8.35 (d, 1H, J = 2.1 Hz), 8.47 (d, 1H,

C. Lamberth et al. / Bioorg. Med. Chem. 22 (2014) 3922–3930

J = 2.0 Hz), 8.54 (d, 1H, J = 2.2 Hz), 9.06 (d, 1H, J = 2.1 Hz). LC-MS: Rt = 1.94 min; MS: m/z = 268 [M]+, 269 [M+1]+. 4.1.2. 3-Bromo-6-methoxy-8-methylquinoline (6) 2,2,3-Tribromopropanal (50.0 g, 0.18 mol) was slowly added to a suspension of 4-methoxy-2-methylaniline (5, 25.0 g, 0.18 mol) in 300 ml of glacial acetic acid. The reaction mixture was stirred for 6 h at room temperature, then diluted with ethyl acetate and washed with water, brine and 2 N sodium hydroxide solution, subsequently dried over magnesium sulfate and evaporated under reduced pressure. The residue was purified by chromatography on silica gel, using ethyl acetate and heptane as eluents to yield 3-bromo-6-methoxy8-methylquinoline (6, 20.5 g, 81 mmol, 45%). 1H NMR (CDCl3): d = 2.73 (s, 3H), 3.90 (s, 3H), 6.82 (d, 1H, J = 2.0 Hz), 7.21 (d, 1H, J = 2.1 Hz), 8.17 (d, 1H, J = 1.9 Hz), 8.76 (d, 1H, J = 2.0 Hz). LC-MS: Rt = 1.99 min; MS: m/z = 254 [M]+, 255 [M+1]+. 4.1.3. 3-Bromo-8-methylquinolin-6-ol (7) From 4: reduced iron powder (15 g, 0.27 mol) was added in portions to a suspension of 3-bromo-8-methyl-6-nitroquinoline (4, 20.6 g, 77 mmol) in a mixture of 400 ml of ethanol and 2 ml of 37% aqueous hydrochloric acid at room temperature. The reaction mixture was heated to reflux for 2 h, during which the color of the suspension changed from grey–yellow to red–brown. The reaction mixture was cooled to 40 °C, filtered through Celite, the filtrate was diluted with ethanol, treated with silica gel and concentrated under reduced pressure. The residue was purified by chromatography on silica gel, using ethyl acetate and dichloromethane as eluents to deliver 6-amino-3-bromo-8-methylquinoline. This intermediate was suspended in a mixture of 125 ml of 85% aqueous phosphoric acid and 12 ml of water and heated in a tantalum pressure vessel to 180 °C for 72 h. Subsequently, the mixture was cooled to room temperature and poured on water. 30% Aqueous sodium hydroxide was added to this solution until pH 2–4 was reached. The precipitate formed was filtered, washed with cold water and dried to give 3bromo-8-methylquinolin-6-ol (7, 12.3 g, 52 mmol, 67%). 1H NMR (DMSO-d6): d = 2.64 (s, 3H), 6.99 (d, 1H, J = 2.1 Hz), 7.22 (d, 1H, J = 2.1 Hz), 8.47 (d, 1H, J = 2.2 Hz), 8.69 (d, 1H, J = 2.3 Hz), 10.13 (s, 1H). LC-MS: Rt = 1.78 min; MS: m/z = 238 [M]+, 239 [M+1]+. From 6: a mixture of 3-bromo-6-methoxy-8-methylquinoline (6, 14.0 g, 55 mmol) in 250 ml of 48% hydrobromic acid was slowly heated to 110 °C and kept at this temperature for 20 h. Subsequently, the reaction mixture was cooled to room temperature and filtered. The residue was washed with water, taken up in saturated aqueous sodium bicarbonate solution and filtered again. The remainder was washed with water and dried in high vacuum to afford 3-bromo-8-methylquinolin-6-ol (7, 11.1 g, 47 mmol, 84%). 1H NMR and LC-MS were identical to those obtained from 4. 4.1.4. 2-(3-Bromo-8-methylquinolin-6-yloxy)-butyric acid methyl ester (8) Potassium carbonate (8.7 g, 63 mmol) was added to a solution of 3-bromo-8-methylquinolin-6-ol (7, 5.0 g, 21 mmol) in 70 ml of N,N-dimethylformamide. After the addition of methyl 2-bromobutyrate (7.1 g, 38 mmol), the reaction mixture was stirred for 16 h at room temperature. Subsequently the mixture was filtered and the filtrate was diluted with ethyl acetate. This organic phase was washed with water and brine, dried over magnesium sulfate and evaporated under reduced pressure. The residue was purified by chromatography on silica gel, using ethyl acetate and cyclohexane as eluents to yield 2-(3-bromo-8-methylquinolin-6-yloxy)-butyric acid methyl ester (8, 6.5 g, 19 mmol, 91%). 1H NMR (CDCl3): d = 1.04 (t, 3H, J = 7.3 Hz), 1.99 (q, 2H, J = 7.1 Hz), 2.68 (s, 3H), 3.70 (s, 3H), 4.63 (t, 1H, J = 7.7 Hz), 6.65 (d, 1H, J = 2.3 Hz), 7.22 (d, 1H, J = 2.2 Hz), 8.06 (d, 1H, J = 2.1 Hz), 8.68 (d, 1H, J = 2.1 Hz). LC-MS: Rt = 1.12 min; MS: m/z = 340 [M+1]+, 341 [M+2]+.

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4.1.5. 2-(3-Bromo-8-methylquinolin-6-yloxy)-N-prop-2-ynylbutyramide (9) Lithium hydroxide hydrate (0.2 g, 5.3 mmol) was added to a solution of 2-(3-bromo-8-methylquinolin-6-yloxy)-butyric acid methyl ester (8, 1.5 g, 4.4 mmol) in a mixture of 11 ml of tetrahydrofuran and 11 ml of water at 0 °C The reaction mixture was stirred for 2 h at 0 °C and then warmed to room temperature. The tetrahydrofuran was evaporated under reduced pressure and 1 N hydrochloric acid was added to the remaining mixture until pH 1 was reached. The precipitate formed was filtered and dried in a vaccum oven at 50 °C to deliver 2-(3-bromo-8-methyl-quinolin-6-yloxy)-butyric acid. This intermediate was dissolved in 30 ml of N,N-dimethylformamide and triethylamine (1.5 g, 15 mmol), 1-hydroxy-7-azabenzotriazole (0.9 g, 6.5 mmol), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (1.2 g, 6.5 mmol) and propargylamine (0.4 g, 6.5 mmol) were added consecutively. The reaction mixture was stirred for 16 h at room temperature, then diluted with ethyl acetate and extracted with brine, saturated aqueous sodium bicarbonate solution and water. The organic layer was dried over magnesium sulfate and evaporated under reduced pressure, the residue was crystallized with t-butyl methyl ether to deliver 2-(3-bromo-8-methylquinolin-6-yloxy)-Nprop-2-ynylbutryramide (9, 0.7 g, 1.9 mmol, 43%). Mp 174–178 °C (%). 1H NMR (CDCl3): d = 1.00 (t, 3H, J = 7.2 Hz), 1.92–2.03 (m, 2H), 2.11 (d, 1H, J = 2.4 Hz), 2.78 (s, 3H), 3.93 (dd, 1 H, J = 2.3 Hz,11.0 Hz), 4.06 (dd, 1H, J = 2.4 Hz, 10.8 Hz), 4.59 (t, 1H, J = 7.5 Hz), 6.45 (br s, 1H), 6.76 (d, 1H, J = 2.0 Hz), 7.22 (d, 1H, J = 2.1 Hz), 8.09 (d, 1H, J = 2.2 Hz), 8.72 (d, 1H, J = 2.1 Hz). LC-MS: Rt = 0.97 min; MS: m/z = 363 [M+1]+, 364 [M+2]+. 4.1.6. 2-(3-Bromo-8-methylquinolin-6-yloxy)-2methylsulfanyl-acetic acid methyl ester (10) Methyl 2-chloro-2-(methylsulfanyl)acetate (11 g, 73 mmol) and milled potassium carbonate (42.5 g, 0.3 mol) were consecutively added to a suspension of 3-bromo-8-methylquinolin-6-ol (7, 14.5 g, 61 mmol) in 200 ml of N,N-dimethylformamide. The reaction mixture was stirred for 2 h at 60 °C, then cooled to room temperature and diluted with ethyl acetate. The organic layer was washed with water, dried over magnesium sulfate and evaporated under reduced pressure. The residue was purified by chromatography on silica gel, using ethyl acetate and hexane as eluents to deliver 2-(3-bromo-8-methylquinolin-6-yloxy)-2-methylsulfanylacetic acid methyl ester (10, 15.5 g, 43 mmol, 71%). 1H NMR (CDCl3): d = 2.23 (s, 3H), 2.74 (s, 3H), 3.87 (s, 3H), 5.72 (s, 1H), 6.96 (d, 1H, J = 2.2 Hz), 7.36 (d, 1H, J = 2.1 Hz), 8.18 (d, 1H, J = 2.0 Hz), 8.80 (d, 1H, J = 2.1 Hz). LC-MS: Rt = 2.04 min; MS: m/z = 358 [M+1]+, 359 [M+2]+. 4.1.7. 2-(3-Bromo-8-methylquinolin-6-yloxy)-2methylsulfanyl-acetic acid (11) 2 N sodium hydroxide (21 ml, 42 mmol) was added to a suspension of 2-(3-bromo-8-methylquinolin-6-yloxy)-2-methylsulfanylacetic acid methyl ester (10, 10 g, 28 mmol) in 65 ml of ethanol. The reaction mixture was stirred for 1 h at room temperature, then cooled to 0 °C and acidified with 2 N hydrochloric acid until pH 2 was reached. The resulting precipitate was filtered and dried in a dessicator to obtain 2-(3-bromo-8-methylquinoline-6-yloxy)-2methylsulfanyl-acetic acid (11, 9.6 g, 28 mmol, 100%). 1H NMR (DMSO-d6): d = 2.17 (s, 3H), 2.68 (s, 3H), 6.06 (s, 1H), 7.32 (d, 1H, J = 2.1 Hz), 7.47 (d, 1H, J = 2.0 Hz), 8.54 (d, 1H, J = 2.1 Hz), 8.83 (d, 1H, J = 2.2 Hz). LC-MS: Rt = 1.95 min; MS: m/z = 344 [M+1]+, 345 [M+2]+. 4.1.8. 2-(3-Bromo-8-methylquinolin-6-yloxy)-N-tert-butyl-2methylsulfanyl-acetamide (12) Triethylamine (1.5 g, 15 mmol), 1-hydroxy-7-azabenzotriazole (2.0 g, 15 mmol), 1-ethyl-3-(3-dimethylamino-propyl)carbodiim-

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ide (2.8 g, 15 mmol) and 2-(3-bromo-8-methylquinoline-6-yloxy)2-methylsulfanyl-acetic acid (11, 5.0 g, 15 mmol) were added consecutively to a solution of tert-butylamine (1.1 g, 15 mmol) in 70 ml of N,N-dimethylformamide. The reaction mixture was stirred for 5 h at room temperature, then diluted with ethyl acetate and extracted with brine, saturated aqueous sodium bicarbonate solution and water. The organic layer was dried over magnesium sulfate and evaporated under reduced pressure, the residue was purified by chromatography on silica gel, using ethyl acetate and hexane as eluents to deliver 2-(3-bromo-8-methylquinolin-6yloxy)-N-tert-butyl-2-methylsulfanyl-acetamide (12, 3.9 g, 9.8 mmol, 67%). 1H NMR (CDCl3): d = 1.43 (s, 9H), 2.19 (s, 3H), 2.78 (s, 3H), 5.56 (s, 1H), 6.43 (br s, 1H), 7.00 (d, 1H, J = 2.1 Hz), 7.31 (d, 1H, J = 2.1 Hz), 8.20 (d, 1H, J = 2.2 Hz), 8.82 (d, 1H, J = 2.0 Hz). LC-MS: Rt = 2.09 min; MS: m/z = 399 [M+1]+, 400 [M+2]+. 4.1.9. 2-Methylsulfanyl-2-(8-methyl-3-vinylquinolin-6-yloxy)acetic acid methyl ester (13) Tetrakis(triphenylphosphine)palladium (130 mg, 0.11 mmol) was added to a solution of 2-(3-bromo-8-methylquinolin-6yloxy)-2-methylsulfanyl-acetic acid methyl ester (10, 2.0 g, 5.6 mmol) and vinyltributyltin (1.8 g, 5.6 mmol) in 50 ml of toluene at room temperature, The reaction mixture was heated to 100 °C for 20 h, then cooled to room temperature. Saturated aqueous sodium carbonate solution was added and the resulting mixture was stirred for 1 h at room temperature, subsequently diluted with ethyl acetate and then extracted with 5% aqueous ammonium hydroxide solution and brine. The organic layer was dried over magnesium sulfate and evaporated under reduced pressure, the residue was purified by chromatography on silica gel, using ethyl acetate and hexane as eluents to deliver 2-methylsulfanyl-(8-methyl-3-vinylquinolin-6-yloxy)acetic acid methyl ester (13, 0.8 g, 2.6 mmol, 47%). 1H NMR (CDCl3): d = 2.25 (s, 3H), 2.78 (s, 3H), 3.89 (s, 3H), 5.47 (d, 1H, J = 11.2 Hz), 5.75 (s, 1H), 5.98 (d, 1H, J = 17.8 Hz), 6.87 (dd, 1H, J = 11.1, 17.7 Hz), 7.06 (d, 1H, J = 2.1 Hz), 7.33 (d, 1H, J = 2.2 Hz), 7.97 (d, 1H, J = 2.0 Hz), 8.94 (d, 1H, J = 2.1 Hz). LC-MS: Rt = 1.77 min; MS: m/z = 304 [M+1]+, 305 [M+2]+. 4.1.10. N-(1-Cyano-2-methoxy-1-methyl-ethyl)-2methylsulfanyl-2-(8-methyl-3-vinylquinolin-6-yloxy)acetamide (14) 0.5 N sodium hydroxide (5 ml, 2.5 mmol) was slowly added at 0 °C to a solution of 2-methylsulfanyl-(8-methyl-3-vinylquinolin6-yloxy)acetic acid methyl ester (13, 0.6 g, 2.0 mmol) in 20 ml of tetrahydrofuran. The reaction mixture was stirred for 1 h at 0 °C, then 1 N hydrochloric acid was added to the remaining mixture until pH 3 was reached. The mixture was extracted with ethyl acetate, the organic layer was washed with water and brine, dried over magnesium sulfate and evaporated under reduced pressure to deliver 2-methylsulfanyl-(8-methyl-3-vinylquinolin-6-yloxy)acetic acid. This intermediate was dissolved in 17 ml of acetonitrile, and triethylamine (0.35 g, 3.4 mmol), 1-hydroxy-7-azabenzotriazole (0.1 g, 0.8 mmol), O-(benzotriazolyl-1-yl)-N,N,N0 ,N0 -tetramethyluronium tetrafluoroborate (0.24 g, 0.8 mmol) and 2-amino3-methoxy-2-methyl-propionitrile (90 mg, 0.8 mmol) were added consecutively. The reaction mixture was stirred for 16 h at room temperature, then diluted with ethyl acetate and extracted with brine, saturated aqueous sodium bicarbonate solution and water. The organic layer was dried over magnesium sulfate and evaporated under reduced pressure. The residue was purified by chromatography on silica gel, using ethyl acetate and cyclohexane as eluents to deliver N-(1-cyano-2-methoxy-1-methylethyl)-2-methylsulfanyl-2-(8-methyl-3-vinylquinolin-6-yloxy)-acetamide (14,

0.38 g, 1.0 mmol, 49% over two steps). 1H NMR (CDCl3): d = 1.82 (d, 3H), 2.23 (s, 3H), 2.81 (s, 3H), 3.51 (d, 3H), 3.68–3.82 (m, 2H), 5.49 (d, 1H, J = 11.1 Hz), 5.74 (d, 1H), 5.99 (d, 1H, J = 17.7 Hz), 6.88 (dd, 1H, J = 11.0, 17.7 Hz), 7.12 (d, 1H, J = 2.0 Hz), 7.28 (d, 1H, J = 2.1 Hz), 8.00 (d, 1H, J = 2.0 Hz), 8.97 (d, 1H, J = 2.2 Hz). LCMS: Rt = 1.71 min; MS: m/z = 386 [M+1]+, 387 [M+2]+. 4.1.11. 2-(3-Ethynyl-8-methylquinolin-6-yloxy)-2methylsulfanyl-acetic acid methyl ester (15) Trimethylsilylacetylene (4.1 g, 42 mmol) was added dropwise to a degassed solution of 2-(3-bromo-8-methylquinolin-6-yloxy)2-methylsulfanyl-acetic acid methyl ester (10, 10 g, 28 mmol), copper iodide (0.2 g, 1.4 mmol), diisopropylamine (5.7 g, 56 mmol) and bis(triphenylphosphine)palladium(II) dichloride (1.0 g, 1.4 mmol) in 150 ml of tetrahydrofuran. The reaction mixture was stirred for 24 h at room temperature and then washed with brine. The aqueous phase was extracted with ethyl acetate, the combined organic layer washed with water, dried over magnesium sulfate and evaporated under reduced pressure. The residue was purified by chromatography on silica gel, using ethyl acetate and heptane as eluents to deliver 2-methylsulfanyl-(8-methyl-3-trimethylsilanylethynyl-quinolin-6-yloxy)-acetic acid methyl ester. This intermediate was dissolved in 200 ml of methanol and treated with potassium carbonate (8.1 g, 59 mmol). The reaction mixture was stirred for 30 min at room temperature, then poured on saturated aqueous sodium bicarbonate solution and extracted with ethyl acetate. The organic layer was dried over magnesium sulfate and evaporated under reduced pressure, the residue was purified by chromatography on silica gel, using ethyl acetate and heptane as eluents to deliver 2-(3-ethynyl-8-methylquinolin-6-yloxy)-2methylsulfanyl-acetic acid methyl ester (15, 4.6 g, 15 mmol, 54%) 1 H NMR (CDCl3): d = 2.24 (s, 3H), 2.78 (s, 3H), 3.27 (s, 1H), 3.88 (s, 3H), 5.73 (s, 1H), 7.02 (d, 1H, J = 2.1 Hz), 7.37 (d, 1H, J = 2.1 Hz), 8.16 (d, 1H, J = 2.1 Hz), 8.85 (d, 1H, J = 2.0 Hz). LC-MS: Rt = 1.87 min; MS: m/z = 302 [M+1]+, 303 [M+2]+. 4.1.12. 2-(3-Ethynyl-8-methylquinolin-6-yloxy)-N-(2methoxyimino-1,1-dimethyl-ethyl)-2-methyl-sulfanylacetamide (2) 2 N sodium hydroxide (3.1 ml, 6.3 mmol) was added to a solution of 2-(3-ethynyl-8-methylquinolin-6-yloxy)-2-methylsulfanyl-acetic acid methyl ester (15, 1.2 g, 4.2 mmol) in 50 ml of ethanol. The reaction mixture was stirred for 1 h at room temperature, then 2 N hydrochloric acid was added to the remaining mixture until pH 3 was reached. The mixture was poured on brine and extracted with ethyl acetate. The organic layer was dried over magnesium sulfate and evaporated under reduced pressure to deliver 2-(3-ethynyl8-methylquinolin-6-yloxy)-2-methylsulfanyl-acetic acid. This intermediate was dissolved in 12 ml of N,N-dimethylformamide and, triethylamine (0.4 g, 4.4 mmol), 1-hydroxy-7-azabenzotriazole (0.6 g, 4.4 mmol), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (0.8 g, 4.4 mmol) and 2-amino-2-methyl-propionaldehyde O-methyl-oxime hydrochloride (0.7 g, 4.4 mmol) were added consecutively. The reaction mixture was stirred for 16 h at room temperature, then diluted with ethyl acetate and extracted with brine. The organic layer was dried over magnesium sulfate and evaporated under reduced pressure, the residue was purified by chromatography on silica gel, using ethyl acetate and hexane as eluents to deliver 2-(3-ethynyl-8-methylquinolin-6-yloxy)N-(2-methoxyimino-1,1-dimethyl-ethyl)-2-methylsulfanyl-acetamide (2, 0.9 g, 2.3 mmol, 56% over two steps). 1H NMR (CDCl3): d = 1.59 (s, 3H), 1.62 (s, 3H), 2.21 (s, 3H), 2.79 (s, 3H), 3.31 (s, 1H), 3.89 (s, 3H), 5.66 (s, 1H), 7.06 (d, 1H, J = 2.1 Hz), 7.33 (d, 1H, J = 2.2 Hz), 7.59 (s, 1H), 8.17 (d, 1H, J = 2.2 Hz), 8.85 (d, 1H, J = 2.1 Hz). LC-MS: Rt = 1.88 min; MS: m/z = 386 [M+1]+, 387 [M+2]+.

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4.1.13. 2-(3,8-Dimethylquinolin-6-yloxy)-2-methyl-sulfanylacetic acid methyl ester (16) A degassed solution of 2-(3-bromo-8-methylquinolin-6-yloxy)2-methylsulfanyl-acetic acid methyl ester (10, 4.0 g, 11 mmol), trimethylboroxine (1.5 g, 12 mmol), potassium carbonate (4.7 g, 34 mmol) and tetrakis(triphenylphosphine)palladium(0) (1.3 g, 1.1 mmol) in 90 ml of dioxane was heated to 100 °C for 5 h. The reaction mixture was cooled to room temperature, then diluted with ethyl acetate and extracted with water. The organic layer was washed with brine, dried over magnesium sulfate and concentrated under reduced pressure. The residue was purified by chromatography on silica gel, using ethyl acetate and cyclohexane as eluents to deliver 2-(3,8-dimethylquinolin-6-yloxy)-2-methylsulfanyl-acetic acid methyl ester (16, 1.7 g, 5.7 mmol, 51%). 1H NMR (CDCl3): d = 2.26 (s, 3H), 2.51 (s, 3H), 2.78 (s, 3H), 3.87 (s, 3H), 5.74 (s, 1H), 6.99 (d, 1H, J = 2.1 Hz), 7.31 (d, 1H, J = 2.1 Hz), 7.82 (d, 1H, J = 2.2 Hz), 8.69 (d, 1H, J = 2.1 Hz). LC-MS: Rt = 1.45 min; MS: m/z = 292 [M+1]+, 293 [M+2]+. 4.1.14. 2-(3,8-Dimethylquinolin-6-yloxy)-N-(4-methoxy-1,1dimethyl-but-2-ynyl)-2-methylsulfanyl-acetamide (17) 1 N sodium hydroxide (7.5 ml, 7.5 mmol) was added to a solution of 2-(3,8-dimethylquinolin-6-yloxy)-2-methylsulfanyl-acetic acid methyl ester (16, 1.7 g, 5.7 mmol) in 25 ml of tetrahydrofuran at 0 °C. The reaction mixture was stirred for 1 h at room temperature, then 2 N hydrochloric acid was added to the remaining mixture until pH 3 was reached. The mixture was poured on brine and extracted with ethyl acetate. The organic layer was dried over magnesium sulfate and evaporated under reduced pressure to deliver 2-(3,8-dimethylquinolin-6-yloxy)-2-methylsulfanyl-acetic acid. This intermediate was dissolved in 80 ml of acetonitrile and triethylamine (2.0 g, 20 mmol), 1-hydroxy-7-azabenzotriazole (1.1 g, 8.5 mmol), O-(benzotriazolyl-1-yl)-N,N,N0 ,N0 -tetramethyluronium tetrafluoroborate (2.7 g, 8.5 mmol) and 4-methoxy-1,1-dimethylbut-2-ynylamine hydrochloride (1.4 g, 8.5 mmol) were added consecutively. The reaction mixture was stirred for 16 h at room temperature, then diluted with ethyl acetate and extracted with brine, saturated aqueous sodium bicarbonate solution and water. The organic layer was dried over magnesium sulfate and evaporated under reduced pressure. The residue was purified by chromatography on silica gel, using ethyl acetate and cyclohexane as eluents to deliver 2-(3,8-dimethylquinolin-6-yloxy)-N-(4-methoxy-1,1-dim ethyl-but-2-ynyl)-2-methylsulfanyl-acetamide (17, 1.7 g, 4.6 m mol, 82% over two steps). 1H NMR (CDCl3): d = 1.74 (s, 6H), 2.21 (s, 3H), 2.50 (s, 3H), 2.78 (s, 3H), 3.38 (s, 3H), 4.13 (s, 2H), 5.63 (s, 1H), 6.78 (br s, 1H), 7.03 (d, 1H, J = 2.0 Hz), 7.24 (d, 1H, J = 2.1 Hz), 7.82 (d, 1H, J = 2.0 Hz), 8.70 (d, 1H, J = 2.2 Hz). LC-MS: Rt = 1.54 min; MS: m/z = 387 [M+1]+, 388 [M+2]+. 4.1.15. 2-(3-Cyclopropyl-8-methylquinolin-6-yloxy)-2methylsulfanyl-acetic acid methyl ester (18) Tetrakis(triphenylphosphine)palladium(0) (0.3 g, 0.3 mmol) was added to a degassed solution of 2-(3-bromo-8-methylquinolin-6-yloxy)-2-methylsulfanyl-acetic acid methyl ester (10, 2.0 g, 5.6 mmol), cyclopropyl boronic acid (0.6 g, 7.3 mmol) and potassium phosphate tribasic (4.1 g, 19 mmol) in 40 ml of toluene and 2 ml of water. The reaction mixture was heated to 100 °C for 5 h, then cooled to room temperature, diluted with ethyl acetate and extracted with saturated aqueous sodium bicarbonate solution. The organic layer was washed with brine, dried over magnesium sulfate and evaporated under reduced pressure. The residue was purified by chromatography on silica gel, using ethyl acetate and cyclohexane as eluents to deliver 2-(3-cyclopropyl-8-methylquinolin-6-yloxy)-2-methylsulfanyl-acetic acid methyl ester (18, 0.45 g, 1.4 mmol, 25%). 1H NMR (CDCl3): d = 0.87 (q, 2H), 1.12 (q, 2H), 2.04–2.11 (m, 1H), 2.27 (s, 3H), 2.78 (s, 3H), 3.89 (s, 3H),

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5.73 (s, 1H), 7.01 (d, 1H, J = 2.2 Hz), 7.30 (d, 1H, J = 2.1 Hz), 7.63 (d, 1H, J = 2.0 Hz), 8.69 (d, 1H, J = 2.1 Hz). LC-MS: Rt = 1.70 min; MS: m/z = 318 [M+1]+, 319 [M+2]+. 4.1.16. N-(2-Chloroallyl)-2-(3-cyclopropyl-8-methylquinolin-6yloxy)-2-methylsulfanyl-acetamide (19) 0.5 N sodium hydroxide (2.6 ml, 1.3 mmol) was added to a solution of 2-(3-cyclopropyl-8-methylquinolin-6-yloxy)-2-methylsulfa nyl-acetic acid methyl ester (18, 0.32 g, 1.0 mmol) in 10 ml of tetrahydrofuran at 0 °C. The reaction mixture was stirred for 2 h at room temperature, then 2 N hydrochloric acid was added to the remaining mixture until pH 3 was reached. The mixture was poured on brine and extracted with ethyl acetate. The organic layer was dried over magnesium sulfate and evaporated under reduced pressure to deliver 2-(3-cyclopropyl-8-methylquinolin-6-yloxy)-2-methylsulfanyl-acetic acid. This intermediate was dissolved in 5 ml of N,N-dimethylformamide and, triethylamine (0.25 g, 2.5 mmol), 1-hydroxy-7-azabenzotriazole (0.17 g, 1.2 mmol), 1-ethyl-3-(3dimethylaminopropyl)carbodiimide (0.24 g, 1.2 mmol) and 2-chloroallylamine (0.11 g, 1.2 mmol) were added consecutively. The reaction mixture was stirred for 16 h at room temperature, then diluted with ethyl acetate and extracted with saturated aqueous sodium bicarbonate solution. The organic layer was washed with brine, dried over magnesium sulfate and evaporated under reduced pressure, the residue was purified by chromatography on silica gel, using ethyl acetate and cyclohexane as eluents to deliver N-(2-chloroallyl)-2–3-cyclopropyl-8-methylquinolin-6-yloxy)-2-methylsulfanyl-acetamide (19, 0.21 g, 0.55 mmol, 56% over two steps). 1H NMR (CDCl3): d = 0.73–0.81 (m, 2H), 1.01–1.08 (q, 2H), 1.96–2.02 (m, 1H), 2.14 (s, 3H), 2.69 (s, 3H), 4.03 (dd, 1H, J = 11.2, 17.3 Hz), 4.20 (dd, 1H, J = 11.0, 17.3 Hz), 5.27 (s, 1H), 5.36 (s, 1H), 5.65 (s, 1H), 6.92 (br s, 1H), 6.97 (d, 1H, J = 2.2 Hz), 7.18 (d, 1H, J = 2.1 Hz), 7.55 (d, 1H, J = 2.0 Hz), 8.61 (d, 1H, J = 2.1 Hz). LC-MS: Rt = 0.87 min; MS: m/z = 377 [M+1]+, 379 [M+3]+. 4.2. Biology 4.2.1. Phytophthora infestans/tomato (action against late blight on tomato) Three-week old tomato plants cv. Roter Gnom were sprayed in a spray chamber with the formulated test compound diluted in water. The test plants were inoculated by spraying them with a sporangia suspension two days after application. The inoculated test plants were incubated at 18 °C with 14 h light/day and 100% rh in a growth chamber and the percentage leaf area covered by disease was assessed when an appropriate level of disease appeared on untreated check plants (5–7 days after application). 4.2.2. Mycosphaerella graminicola (Septoria tritici)/wheat (action against leaf blotch on wheat) Two-week old wheat plants cv. Riband were sprayed in a spray chamber with the formulated test compound diluted in water. The test plants were inoculated by spraying a spore suspension on them one day after application. After an incubation period of 1 day at 22 °C/21 °C (day/night) and 95% rh, the inoculated test plants were kept at 22 °C/21 °C (day/night) and 70% rh in a greenhouse. Efficacy was assessed directly when an appropriate level of disease appeared on untreated check plants (16–19 days after application). 4.2.3. Uncinula necator (Erysiphe necator)/grape (action against powdery mildew on grape) Five-week old grape seedlings cv. Gutedel were sprayed in a spray chamber with the formulated test compound diluted in water. The test plants were inoculated by shaking plants infected with grape powdery mildew above them 1 day after application.

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