Organic & Biomolecular Chemistry View Article Online

Published on 16 April 2014. Downloaded by University of California - Davis on 11/05/2014 11:19:08.

PAPER

View Journal

Cite this: DOI: 10.1039/c4ob00513a

Received 7th March 2014, Accepted 16th April 2014

Synthesis of α,β-unsaturated amides and iminocoumarins from N,N-disulfonyl ynamides with aldehydes via the ketenimine intermediate† Lian Yu and Jian Cao*

DOI: 10.1039/c4ob00513a

A novel synthesis of α,β-unsaturated amides from N,N-disulfonyl ynamides with aldehydes was developed.

www.rsc.org/obc

By utilization of salicylaldehydes, a variety of substituted iminocoumarins were prepared.

Introduction Ketenimines, as analogues of ketenes, are versatile intermediates which are prone to undergo various organic reactions. Thus their formation and reactivity have been widely investigated.1 Recently, Chang et al. reported the in situ formation of N-sulfonyl ketenimine via copper-catalyzed azide–alkyne cycloaddition (Scheme 1a).2 Based on this method, a series of multi-component reactions were developed.3 Ynamides have emerged as important synthons in modern organic synthesis.4 An array of synthetic targets including indole,5 amidobenzofuran,6 allenamide,7 and amidine8 have been constructed from ynamides. Recently, Hsung and co-workers developed an

elegant synthesis of amidines from N-allyl ynamides via palladium-catalyzed allyl transfer in which N-sulfonyl ketenimine/ynamido-palladium-π-allyl complexes were formed (Scheme 1b).9 Previously we reported a catalyst-free hydroamination reaction of N,N-disulfonyl ynamides10 where N-sulfonyl ketenimine was proposed to be the intermediate.11 We anticipate that the desulfonylation of N,N-disulfonyl ynamides with an appropriate nucleophile could easily produce the N-sulfonyl ketenimine intermediate which would undergo further transformation (Scheme 1c). Herein we wish to report the novel synthesis of α,β-unsaturated amides and iminocoumarins from N,N-disulfonyl ynamides with aldehydes.

Results and discussion

Scheme 1

Key Laboratory of Organosilicon Chemistry and Material Technology of Ministry of Education, Hangzhou Normal University, Wenyi Road 222, Hangzhou 310012, P. R. China. E-mail: [email protected] † Electronic supplementary information (ESI) available. CCDC 979066. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/ c4ob00513a

This journal is © The Royal Society of Chemistry 2014

The initial studies focused on the reaction of N,N-disulfonyl ynamide 2a with the aldehyde 3a. n-PrOLi 1a was chosen as the nucleophile to generate the N-sulfonyl ketenimine. Fortunately, the expected α,β-unsaturated amide 4a was obtained in 77% yield (Table 1, entry 1). Changing the ratio of substrates 1a, 2a and 3a showed that 2.0 : 1.0 : 1.5 (1a : 2a : 3a) gave the best results (entries 1–4). Subsequent screening of solvents showed that tetrahydrofuran was the best choice, and that the use of other common solvents, such as dichloromethane, toluene or 1,4-dioxane, did not improve the yield (entries 5–7). Lowering the reaction temperature reduced the yield dramatically (entry 8). Thus the following reaction conditions were chosen as optimum for all subsequent reactions: 1.0 mmol of n-PrOLi 1a, 0.5 mmol of ynamide 2, and 0.75 mmol of aldehyde 3 in THF were stirred at rt under N2. Under the optimized conditions, the scope of this reaction was further investigated. The reaction was successful for various N,N-disulfonyl ynamides 2. The R1 group of ynamide 2 can be a phenyl group optionally substituted with either an electron-donating or an electron-withdrawing group (Table 2, entries 1–5). A variety of aryl aldehydes were efficiently coupled

Org. Biomol. Chem.

View Article Online

Published on 16 April 2014. Downloaded by University of California - Davis on 11/05/2014 11:19:08.

Paper

Organic & Biomolecular Chemistry

Table 1

Optimization of the reaction conditionsa

Entry

Ratio (1a : 2a : 3a)

Solvent

Temp

Yield of 4a (%)

1 2 3 4 5 6 7 8

3 : 1 : 1.5 2 : 1 : 1.5 1.2 : 1 : 1.5 2 : 1 : 1.2 2 : 1 : 1.5 2 : 1 : 1.5 2 : 1 : 1.5 2 : 1 : 1.5

THF THF THF THF CH2Cl2 Toluene Dioxane THF

rt rt rt rt rt rt rt −78 °C

77 81 59 50 69 32 57 39

Fig. 1

a The reaction was carried out using 1a, 2a (0.5 mmol), and 3a in the solvent (4 mL) under N2.

Table 2

Table 3

ORTEP representation of 4j.

Synthesis of iminocoumarins 6a

Synthesis of α,β-unsaturated amides 4a

Entry

2

R1

3

R2

Yield (%)

1 2 3 4 5 6 7 8 9 10

2a 2b 2c 2d 2e 2a 2a 2a 2a 2c

Ph p-FC6H4 p-ClC6H4 p-PrC6H4 p-MeOC6H4 Ph Ph Ph Ph p-ClC6H4

3a 3a 3a 3a 3a 3b 3c 3d 3e 3f

p-ClC6H4 p-ClC6H4 p-ClC6H4 p-ClC6H4 p-ClC6H4 Ph p-MeC6H4 p-MeOC6H4 o-BrC6H4 α-Furyl

81 (4a) 88 (4b) 90 (4c) 94 (4d) 96 (4e) 81 (4f) 82 (4g) 86 (4h) 56 (4i) 84 (4j)

a The reaction was carried out using 1a (1.0 mmol), 2 (0.5 mmol), and 3 (0.75 mmol) in THF (4 mL) at rt under N2.

to give the corresponding α,β-unsaturated amides 4 (entries 1 and 6–9). Heteroaryl aldehydes such as furfural also afforded the desired product 4j in good yield (entry 10). However alkyl aldehydes and ketones failed to give the corresponding amides. In all reactions in Table 2, the E isomer was obtained as the sole product and the stereochemistry was revealed by X-ray diffraction of 4j (Fig. 1).12 When salicylaldehyde was used in this reaction, the additional nucleophile was not necessary. In the presence of a weak base Et3N, ynamides 2 reacted smoothly with salicylaldehydes 5 to afford iminocoumarins 6 under mild conditions, and α,β-unsaturated amides were not found (Table 3). It should be noted that 3.0 equiv. of salicylaldehyde 5 was required to promote the reaction. In these reactions, the benzenesulfonic esters PhSO2OPr or PhSO2OAr were detected as byproducts; we therefore propose the mechanism shown in Scheme 2. (a) Desulfonylation of N,N-disulfonyl ynamide 2 with n-PrOLi 1 affords the intermedi-

Org. Biomol. Chem.

a The reaction was carried out using 2 (0.5 mmol), 5 (1.5 mmol), and Et3N (0.5 mL) in CH2Cl2 (4 mL) at rt under N2.

ate A, which undergoes an addition reaction with the aldehyde 3 to form B. Subsequent formation and ring-opening of oxetene C gives the amide D, which is protonated to produce the α,β-unsaturated amide 4 after workup. Based on Houk’s seminal theoretical work13,14 on illustrating the preference for an outward rotation of an electron-donating group (alkyl or aryl) in the 4e-electrocyclic ring opening of cyclobutenes, outward conrotatory rotation would be favored to give the E-product.15 (b) Desulfonylation of N,N-disulfonyl ynamide 2 with salicylaldehyde 5 in the presence of Et3N leads to the formation of the ketenimine intermediate E. Addition of the second molecule of 5 and subsequent intramolecular

This journal is © The Royal Society of Chemistry 2014

View Article Online

Organic & Biomolecular Chemistry

Paper

prior to use. All 1H NMR and 13C NMR spectra were measured in CDCl3 or DMSO-d6 with TMS as the internal standard. Chemical shifts are expressed in ppm and J values are given in Hz.

Published on 16 April 2014. Downloaded by University of California - Davis on 11/05/2014 11:19:08.

General procedures for synthesis of α,β-unsaturated amides 4

Scheme 2

nucleophilic addition and dehydration generate iminocoumarin 6.

Conclusions In summary, we have reported a novel synthesis of α,β-unsaturated amides from N,N-disulfonyl ynamides with aldehydes. A variety of substituted iminocoumarins were prepared by utilization of salicylaldehydes. Plausible mechanisms involving the ketenimine intermediate are proposed to explain this reaction.

Experimental General All reactions were performed under a N2 atmosphere. All solvents were purified and dried according to standard methods

This journal is © The Royal Society of Chemistry 2014

A vial was charged with the ynamide 2 (0.5 mmol) and the aldehyde 3 (0.75 mmol) and evacuated under high vacuum and backfilled with N2. THF (3 mL) was added and the solution was stirred at rt. The solution of n-PrOLi 1a (1 mmol, prepared from n-PrOH and n-BuLi) in THF (1 mL) was next added and the solution was stirred at rt. After 2 was consumed (1–4 h, TLC, eluent: hexane–EtOAc, 6 : 1), the mixture was quenched with a saturated NH4Cl solution. The phases were separated and the aqueous layer was extracted with EtOAc. The combined organic layers were washed with brine, dried over Na2SO4 and concentrated under reduced pressure. The residue was purified by flash chromatography on silica gel (eluent: hexane–EtOAc, 6 : 1–4 : 1) to afford 4. 4a Yield: 161.0 mg (81%). Light-gray solid, mp: 172–174 °C. 1 H NMR (400 MHz, DMSO-d6): δ 7.93 (2H, d, J = 7.2 Hz), 7.57 (1H, s), 7.48–7.50 (3H, m), 7.27–7.29 (3H, m), 7.17 (2H, d, J = 8.4 Hz), 7.04–7.06 (2H, m), 6.94–6.96 (2H, m); 13C NMR (100 MHz, DMSO-d6): δ 167.6, 140.3, 138.2, 135.6, 135.1, 134.7, 133.9, 130.5, 130.0, 129.6, 129.5, 129.1, 128.7, 128.5, 128.1; IR (KBr, cm−1): 3259, 1692, 1620, 1404, 1336, 1133, 1083; HRMS (m/z) calcd for C21H17ClNO3S (M + H)+: 398.0612, found: 398.0610. 4b Yield: 183.5 mg (88%). Light-gray solid, mp: 189–191 °C. 1 H NMR (400 MHz, DMSO-d6): δ 12.29 (1H, br, s), 7.93 (2H, d, J = 7.2 Hz), 7.52–7.64 (4H, m), 7.26–7.28 (2H, m), 7.13–7.15 (2H, m), 7.00–7.06 (4H, m); 13C NMR (100 MHz, DMSO-d6): δ 167.9, 163.5, 161.1, 141.2, 136.6, 135.8, 133.91, 133.87, 133.3, 132.3, 132.2, 132.0, 129.3, 128.9, 127.9, 116.1, 115.9; IR (KBr, cm−1): 3047, 1508, 1316, 1295, 1131, 1087; HRMS (m/z) calcd for C21H15ClFNNaO3S (M + Na)+: 438.0337, found: 438.0341. 4c Yield: 194.4 mg (90%). Light-gray solid, mp: 206–208 °C. 1 H NMR (400 MHz, DMSO-d6): δ 7.80 (2H, d, J = 7.6 Hz), 7.51 (1H, s), 7.39–7.42 (3H, m), 7.32 (2H, d, J = 8.4 Hz), 7.21 (2H, d, J = 8.4 Hz), 7.02 (2H, d, J = 8.4 Hz), 6.94 (2H, d, J = 8.4 Hz); 13 C NMR (100 MHz, DMSO-d6): δ 168.0, 141.7, 136.4, 136.3, 134.9, 133.9, 133.8, 133.1, 133.0, 132.1, 132.0, 129.1, 129.0, 128.9, 127.9; IR (KBr, cm−1): 3264, 1698, 1404, 1335, 1131, 1086; HRMS (m/z) calcd for C21H15Cl2NNaO3S (M + Na)+: 454.0042, found: 454.0053. 4d Yield: 206.2 mg (94%). Light-gray solid, mp: 181–183 °C. 1 H NMR (400 MHz, CDCl3): δ 8.07 (3H, m), 7.71 (1H, s), 7.52–7.66 (3H, m), 7.27 (2H, d, J = 7.6 Hz), 7.07 (4H, m), 6.83 (2H, d, J = 8.8 Hz), 2.64 (2H, t, J = 7.6 Hz), 1.69–1.73 (2H, m), 0.98 (3H, t, J = 8.8 Hz); 13C NMR (100 MHz, CDCl3): δ 164.5, 144.5, 139.6, 138.6, 135.6, 134.0, 132.5, 131.9, 130.9, 130.4, 129.5, 128.9, 128.60, 128.57, 37.8, 24.2, 13.9; IR (KBr, cm−1): 2957, 1693, 1403, 1337, 1167, 1133, 1086; HRMS (m/z) calcd for C24H23ClNO3S (M + H)+: 440.1082, found: 440.1081. 4e Yield: 204.8 mg (96%). Light-gray solid, mp: 179–181 °C. 1 H NMR (400 MHz, DMSO-d6): δ 12.21 (1H, br, s), 7.97–7.99

Org. Biomol. Chem.

View Article Online

Published on 16 April 2014. Downloaded by University of California - Davis on 11/05/2014 11:19:08.

Paper

(2H, m), 7.59–7.69 (3H, m), 7.41 (1H, s), 7.26 (2H, d, J = 8.8 Hz), 7.06 (2H, d, J = 8.8 Hz), 6.87–6.96 (4H, m), 3.73 (3H, s); 13 C NMR (100 MHz, DMSO-d6): δ 167.6, 159.6, 140.0, 136.4, 135.2, 134.04, 133.97, 133.88, 132.0, 131.3, 129.5, 128.9, 128.1, 126.8, 114.7, 55.5; IR (KBr, cm−1): 3273, 1692, 1400, 1168, 1132, 1085, 825; HRMS (m/z) calcd for C22H18ClNNaO4S (M + Na)+: 450.0537, found: 450.0553. 4f Yield: 147.5 mg (81%). Light-gray solid, mp: 146–148 °C. 1 H NMR (400 MHz, DMSO-d6): δ 12.29 (1H, br, s), 7.98 (2H, d, J = 7.2 Hz), 7.58–7.67 (3H, m), 7.53 (1H, s), 7.31–7.33 (3H, m), 7.14–7.21 (3H, m), 7.01–7.03 (4H, m); 13C NMR (100 MHz, DMSO-d6): δ 167.6, 140.3, 138.2, 135.6, 135.1, 134.7, 133.9, 130.5, 130.0, 129.5, 129.4, 129.1, 128.7, 128.5, 128.1; IR (KBr, cm−1): 3049, 1701, 1395, 1336, 1168, 1126, 1088; HRMS (m/z) calcd for C21H18NO3S (M + H)+: 364.1002, found: 364.1006. 4g Yield: 155.5 mg (82%). Light-gray solid, mp: 109–111 °C. 1 H NMR (400 MHz, DMSO-d6): δ 7.99 (2H, d, J = 6.4 Hz), 7.53–7.65 (4H, m), 7.30–7.33 (3H, m), 6.89–7.04 (6H, m), 2.18 (3H, s); 13C NMR (100 MHz, DMSO-d6): δ 167.9, 140.8, 139.4, 138.1, 136.0, 134.6, 133.6, 132.0, 130.6, 130.1, 129.4, 129.0, 128.3, 128.0, 21.3; IR (KBr, cm−1): 3241, 1677, 1396, 1331, 1169, 1086; HRMS (m/z) calcd for C22H19NNaO3S (M + Na)+: 400.0978, found: 400.0986. 4h Yield: 169.5 mg (86%). Light-gray solid, mp: 139–141 °C. 1 H NMR (400 MHz, DMSO-d6): δ 12.16 (1H, br, s), 8.00 (2H, m), 7.55–7.66 (4H, m), 7.33–7.35 (3H, m), 6.97–7.06 (4H, m), 6.74–6.75 (2H, m), 3.68 (3H, s); 13C NMR (100 MHz, DMSO-d6): δ 167.6, 160.5, 140.5, 138.4, 136.0, 133.8, 132.6, 132.4, 130.1, 129.4, 129.2, 128.4, 128.1, 127.0, 114.3, 55.6; IR (KBr, cm−1): 3262, 1692, 1404, 1252, 1127, 1087; HRMS (m/z) calcd for C22H19NNaO4S (M + Na)+: 416.0927, found: 416.0936. 4i Yield: 124.3 mg (56%). Light-gray solid, mp: 188–190 °C. 1 H NMR (400 MHz, DMSO-d6): δ 12.47 (1H, br, s), 7.99 (2H, d, J = 7.2 Hz), 7.62–7.74 (4H, m), 7.49 (1H, s), 7.03–7.24 (5H, m), 6.90–6.92 (2H, m), 6.73 (1H, d, J = 7.6 Hz); 13C NMR (100 MHz, DMSO-d6): δ 167.4, 139.9, 137.5, 136.7, 135.6, 134.5, 134.2, 133.0, 131.4, 130.8, 130.2, 129.6, 128.8, 128.7, 128.1, 127.7, 124.4; IR (KBr, cm−1): 3257, 1693, 1414, 1219, 1132, 906; HRMS (m/z) calcd for C21H17BrNO3S (M + H)+: 442.0107, found: 442.0121. 4j Yield: 162.2 mg (84%). Light-gray solid, mp: 201–203 °C. 1 H NMR (400 MHz, DMSO-d6): δ 7.94 (2H, d, J = 7.2 Hz), 7.41–7.63 (7H, m), 7.12 (2H, d, J = 8.4 Hz), 6.42–6.43 (1H, m), 6.08 (1H, d, J = 3.2 Hz); 13C NMR (100 MHz, DMSO-d6): δ 167.3, 150.5, 145.9, 141.4, 135.1, 133.2, 133.1, 131.9, 131.2, 129.2, 128.8, 127.9, 126.0, 116.0, 112.9; IR (KBr, cm−1): 3265, 1692, 1615, 1399, 1348, 1130, 1084; HRMS (m/z) calcd for C19H14ClNNaO4S (M + Na)+: 410.0224, found: 410.0229. General procedures for synthesis of iminocoumarins 6 A vial was charged with the ynamide 2 (0.5 mmol) and evacuated under high vacuum and backfilled with N2. CH2Cl2 (4 mL), salicylaldehyde 5 (1.5 mmol) and Et3N (0.5 mL) were added successively and the solution was stirred at rt. After 2 was consumed (8–12 h, TLC, eluent: hexane–EtOAc, 6 : 1), the

Org. Biomol. Chem.

Organic & Biomolecular Chemistry

mixture was concentrated under reduced pressure. The residue was purified by flash chromatography on silica gel (eluent: hexane–EtOAc, 6 : 1–4 : 1) to afford 6. 6a Yield: 100.1 mg (55%). Light-yellow solid, mp: 162–164 °C. 1H NMR (400 MHz, CDCl3): δ 8.04 (2H, d, J = 6.8 Hz), 7.67 (1H, s), 7.43–7.57 (7H, m), 7.24–7.35 (5H, m); 13 C NMR (100 MHz, CDCl3): δ 157.6, 152.1, 142.2, 140.1, 134.3, 132.5, 132.0, 129.7, 129.1, 129.0, 128.7, 128.4, 128.3, 127.1, 125.9, 119.8, 116.1; IR (KBr, cm−1): 2924, 1544, 1305, 1085, 858, 730; HRMS (m/z) calcd for C21H15NNaO3S (M + Na)+: 384.0665, found: 384.0668. 6b Yield: 90.1 mg (48%). Light-yellow solid, mp: 190–192 °C. 1H NMR (400 MHz, CDCl3): δ 8.04–8.06 (2H, m), 7.65 (1H, s), 7.47–7.59 (5H, m), 7.30–7.38 (6H, m), 2.40 (3H, s); 13 C NMR (100 MHz, CDCl3): δ 157.8, 150.5, 142.3, 140.0, 135.7, 134.5, 133.1, 132.3, 129.8, 129.1, 128.9, 128.6, 128.2, 128.0, 127.1, 119.6, 116.1, 20.9; IR (KBr, cm−1): 2924, 1525, 1227, 1081, 995, 692; HRMS (m/z) calcd for C22H17NNaO3S (M + Na)+: 398.0821, found: 398.0829. 6c Yield: 90.8 mg (42%). Light-yellow solid, mp: 168–170 °C. 1H NMR (400 MHz, CDCl3): δ 8.05–8.08 (2H, m), 7.26–7.59 (10H, m), 6.61–6.64 (1H, m), 6.51 (1H, d, J = 2.0 Hz), 3.42 (4H, q, J = 7.2 Hz), 1.22 (6H, t, J = 7.2 Hz); 13C NMR (100 MHz, CDCl3): δ 158.7, 155.2, 151.0, 143.1, 141.1, 135.4, 131.9, 129.3, 129.0, 128.4, 128.1, 128.0, 127.0, 122.1, 110.5, 109.5, 96.6, 44.9, 12.5; IR (KBr, cm−1): 2966, 1635, 1502, 1147, 1080, 690; HRMS (m/z) calcd for C25H24N2NaO3S (M + Na)+: 455.1400, found: 455.1397. 6d Yield: 65.3 mg (33%). Light-yellow solid, mp: 198–200 °C. 1H NMR (400 MHz, CDCl3): δ 8.00–8.05 (2H, m), 7.45–7.63 (8H, m), 7.34–7.40 (4H, m); 13C NMR (100 MHz, CDCl3): δ 157.0, 150.6, 142.0, 138.2, 133.9, 132.5, 131.8, 131.3, 131.1, 129.3, 129.0, 128.7, 128.3, 127.3, 127.0, 120.9, 117.9; IR (KBr, cm−1): 3050, 1542, 1262, 1080, 814, 730; HRMS (m/z) calcd for C21H14ClNNaO3S (M + Na)+: 418.0275, found: 418.0268. 6e Yield: 85.8 mg (39%). 1H NMR (400 MHz, CDCl3): δ 8.03 (2H, m), 7.67–7.44 (8H, m), 7.37 (4H, m). Characterization data are consistent with the literature.3a 6f Yield: 80.7 mg (39%). Light-yellow solid, mp: 214–216 °C. 1 H NMR (400 MHz, CDCl3): δ 8.00–8.02 (2H, m), 7.61 (1H, s), 7.47–7.57 (7H, m), 7.39 (1H, d, J = 7.2 Hz), 7.04–7.08 (2H, m); 13 C NMR (100 MHz, CDCl3): δ 164.5, 162.0, 156.8, 150.6, 141.9, 138.1, 132.6, 131.9, 131.2, 131.0, 130.9, 130.3, 129.9, 128.7, 127.3, 127.0, 120.7, 117.9, 115.5, 115.3; IR (KBr, cm−1): 2920, 2850, 1462, 1187, 1080, 966; HRMS (m/z) calcd for C21H13ClFNNaO3S (M + Na)+: 436.0181, found: 436.0180. 6g Yield: 52.8 mg (27%). Light-yellow solid, mp: 175–177 °C. 1H NMR (400 MHz, CDCl3): δ 8.06–8.08 (2H, m), 7.67 (1H, s), 7.47–7.57 (7H, m), 7.32–7.42 (2H, m), 6.90 (2H, d, J = 8.8 Hz), 3.82 (3H, s); 13C NMR (100 MHz, CDCl3): δ 160.2, 157.8, 152.0, 142.2, 138.8, 132.4, 131.6, 130.4, 129.5, 128.6, 128.1, 127.2, 126.6, 125.8, 119.9, 116.3, 113.7, 55.4; IR (KBr, cm−1): 2920, 1534, 1511, 1146, 1083, 821; HRMS (m/z) calcd for C22H17NNaO4S (M + Na)+: 414.0770, found: 414.0768.

This journal is © The Royal Society of Chemistry 2014

View Article Online

Organic & Biomolecular Chemistry

Paper

Acknowledgements

C. Alayrac and L. Tevzadze-Saeftel, Angew. Chem., Int. Ed., 2003, 42, 4257; (f ) J. Cao, Y. Xu, Y. Kong, Y. Cui, Z. Hu, G. Wang, Y. Deng and G. Lai, Org. Lett., 2012, 14, 38. (a) J. Oppenheimer, W. L. Johnson, M. R. Tracey, R. P. Hsung, P.-Y. Yao, R. Liu and K. Zhao, Org. Lett., 2007, 9, 2361; (b) K. Dooleweerdt, T. Ruhland and T. Skrydstrup, Org. Lett., 2009, 11, 221; (c) Y. Kong, K. Jiang, J. Cao, L. Fu, L. Yu, G. Lai, Y. Cui, Z. Hu and G. Wang, Org. Lett., 2013, 15, 422; (d) Y. Kong, L. Yu, L. Fu, J. Cao, G. Lai, Y. Cui, Z. Hu and G. Wang, Synthesis, 2013, 1975. (a) F. Gomes, A. Fadel and N. Rabasso, J. Org. Chem., 2012, 77, 5439; (b) J. Brioche, C. Meyer and J. Cossy, Org. Lett., 2013, 15, 1626; (c) J. Cao, Y. Kong, Y. Deng, G. Lai, Y. Cui, Z. Hu and G. Wang, Org. Biomol. Chem., 2012, 10, 9556. (a) S. Kramer, K. Dooleweerdt, A. T. Lindhardt, M. Rottländer and T. Skrydstrup, Org. Lett., 2009, 11, 4208; (b) N. Shindoh, Y. Takemoto and K. Takasu, Chem. – Eur. J., 2009, 15, 7026. (a) Y. Zhang, K. A. DeKorver, A. G. Lohse, Y.-S. Zhang, J. Huang and R. P. Hsung, Org. Lett., 2009, 11, 899; (b) K. A. DeKorver, R. P. Hsung, A. G. Lohse and Y. Zhang, Org. Lett., 2010, 12, 1840; (c) K. A. DeKorver, W. L. Johnson, Y.-S. Zhang, Y. Zhang, A. G. Lohse and R. P. Hsung, J. Org. Chem., 2011, 76, 5092; (d) K. A. DeKorver, R. P. Hsung, W.-Z. Song, X.-N. Wang and M. C. Walton, Org. Lett., 2012, 14, 3214. The synthesis of N,N-disulfonyl ynamides was recently reported, see: K. Muñiz, Á. Iglesias, P. Becker and J. A. Souto, J. Am. Chem. Soc., 2012, 134, 15505. Y. Kong, L. Yu, Y. Cui and J. Cao, Synthesis, 2014, 183. CCDC 979066. (a) W. Kirmse, N. G. Rondan and K. N. Houk, J. Am. Chem. Soc., 1984, 106, 7989; (b) E. A. Kallel, Y. Wang, D. C. Spellmeyer and K. N. Houk, J. Am. Chem. Soc., 1990, 112, 6759; (c) W. R. Dolbier Jr., H. Koroniak, K. N. Houk and C. Sheu, Acc. Chem. Res., 1996, 29, 471; (d) P. S. Lee, X. Zhang and K. N. Houk, J. Am. Chem. Soc., 2003, 125, 5072. (a) M. Murakami, Y. Miyamoto and Y. Ito, Angew. Chem., Int. Ed., 2001, 40, 189; (b) M. Murakami, Y. Miyamoto and Y. Ito, J. Am. Chem. Soc., 2001, 123, 6441; (c) M. Murakami, M. Hasegawa and H. Igawa, J. Org. Chem., 2004, 69, 587. The same stereoselectivity was reported, see: L. You, Z. F. Al-Rashid, R. Figueroa, S. K. Ghosh, G. Li, T. Lu and R. P. Hsung, Synlett, 2007, 1656.

We are grateful to the National Natural Science Foundation of China (Project no. 21102029) for financial support. 6

Published on 16 April 2014. Downloaded by University of California - Davis on 11/05/2014 11:19:08.

Notes and references 1 For recent reviews, see: (a) G. Kollenz, Sci. Synth., 2006, 23, 351; (b) H. Perst, Sci. Synth., 2006, 23, 781; (c) E. J. Yoo and S. Chang, Curr. Org. Chem., 2009, 13, 1766; (d) P. Lu and Y. Wang, Synlett, 2010, 165; (e) S. H. Kim, S. H. Park, J. H. Choi and S. Chang, Chem. – Asian J., 2011, 6, 2618; (f ) M. Alajarin, M. Marin-Luna and A. Vidal, Eur. J. Org. Chem., 2012, 5637; (g) P. Lu and Y. Wang, Chem. Soc. Rev., 2012, 41, 5687. 2 (a) I. Bae, H. Han and S. Chang, J. Am. Chem. Soc., 2005, 127, 2038; (b) S. H. Cho, E. J. Yoo, I. Bae and S. Chang, J. Am. Chem. Soc., 2005, 127, 16046; (c) E. J. Yoo, I. Bae, S. H. Cho, H. Han and S. Chang, Org. Lett., 2006, 8, 1347; (d) M. P. Cassidy, J. Raushel and V. V. Fokin, Angew. Chem., Int. Ed., 2006, 45, 3154; (e) M. Whiting and V. V. Fokin, Angew. Chem., Int. Ed., 2006, 45, 3157. 3 (a) S. L. Cui, X. F. Lin and Y. G. Wang, Org. Lett., 2006, 8, 4517; (b) S. L. Cui, J. Wang and Y. G. Wang, Org. Lett., 2007, 9, 5023; (c) S. L. Cui, J. Wang and Y. G. Wang, Org. Lett., 2008, 10, 1267; (d) W. Lu, W. Z. Song, D. Hong, P. Lu and Y. G. Wang, Adv. Synth. Catal., 2009, 351, 1768; (e) Y. Shen, S. L. Cui, J. Wang, X. P. Chen, P. Lu and Y. G. Wang, Adv. Synth. Catal., 2010, 352, 1139; (f) H. W. Jin, X. Xu, J. Gao, J. H. Zhong and Y. G. Wang, Adv. Synth. Catal., 2010, 352, 347; (g) Z. Chen, D. Zheng and J. Wu, Org. Lett., 2011, 13, 848. 4 For recent reviews, see: (a) K. A. DeKorver, H. Li, A. G. Lohse, R. Hayashi, Z. Lu, Y. Zhang and R. P. Hsung, Chem. Rev., 2010, 110, 5064; (b) G. Evano, A. Coste and K. Jouvin, Angew. Chem., Int. Ed., 2010, 49, 2840; (c) G. Evano, K. Jouvin and A. Coste, Synthesis, 2013, 17; (d) X. Wang, H. Yeom, L. Fang, S. He, Z. Ma, B. L. Kedrowski and R. P. Hsung, Acc. Chem. Res., 2014, 47, 560. 5 (a) J. R. Dunetz and R. L. Danheiser, J. Am. Chem. Soc., 2005, 127, 5776; (b) B. Witulski and T. Stengel, Angew. Chem., Int. Ed., 1999, 38, 2426; (c) Y. Zhang, R. P. Hsung, X. Zhang, J. Huang, B. W. Slater and A. Davis, Org. Lett., 2005, 7, 1047; (d) P.-Y. Yao, Y. Zhang, R. P. Hsung and K. Zhao, Org. Lett., 2008, 10, 4275; (e) B. Witulski,

This journal is © The Royal Society of Chemistry 2014

7

8

9

10

11 12 13

14

15

Org. Biomol. Chem.

Synthesis of α,β-unsaturated amides and iminocoumarins from N,N-disulfonyl ynamides with aldehydes via the ketenimine intermediate.

A novel synthesis of α,β-unsaturated amides from N,N-disulfonyl ynamides with aldehydes was developed. By utilization of salicylaldehydes, a variety o...
277KB Sizes 1 Downloads 3 Views