Synthesis of (5S,7R,8R)-spiro-{7-methoxycarbonyl-1-aza-4-thia-bicyclo [3, 3, 0]-octane 8, 3'}-benzo[b]thiophene-2'-one (5)
An equimolar mixture of thiosatin 1 (0.36 gm, 2.0 mmol), thiazolidine-2-carboxylic acid 2 (0.26 gm, 2.0 mmol) and methyl acrylate (0.32 gm, 2.0 mmol) in dry acetonitrile (50 ml) was refluxed for 22 h. The reaction was monitored by TLC until the consumption of the reactants. The reaction mixture was filtered, solvent evaporated and the residue was subjected to column chromatography. The petroleum ether/chloroform (4:1) fraction afforded the desired azabicycloadduct 5 as pale brown solid.
Pale brown solid, yield: 0.33g (70%), mp: 105-107°C. IR (KBr): 1710(C = O),1450(C-N), 715(C-S) cm-1. 1H NMR (CDCl3, δ ppm): = 2.29 (1H, t, J = 3.0Hz 7-CH), 2.46(2H, dd, J
1 = 4.2Hz, J
2 = 3.3Hz 6-CH2), 2.50(2H, t, J = 1.2Hz 3-CH2), 2.68(2H, t, J = 2.1Hz 2-CH2), 3.10(3H, s, OCH3), 4.15(1H, t, J = 3.54 Hz, 5-CH), 7.36-7.54(4H, m, ArH). 13C NMR (CDCl3, δ ppm): 35.43(CH2S), 44.58(CH2), 46.34(CH), 85.99(C-N), 125.86-124.32(C = C), 142.58-131.36(CHaro), 175.67(O = C-O), 184.32(C = O). EI-MS: m/z (%) = 321(M+ 38), 275(100), 261(20), 284(15), 234(18). Anal. Calcd. For C15H15NO3S2: C, 56.05%; H, 4.70%; N, 4.36%. Found: C, 56.45%; H, 4.78%; N, 4.76%.
(5R,8R)-spiro-{7-phenyl-1-aza-4-thia-bicyclo [3,3,0]-6-octene-8,3'}-benzo[b] thiophene-2'-one (6)
Coffee brown powder, yield: 0.31g (65%), mp: 95-97°C. IR (KBr): 1720(C = O), 1445(C-N), 690(C-S) cm-1. 1H NMR (CDCl3, δ ppm): = 2.50(2H, t, J = 3.0 Hz, 3-CH2), 2.68(2H, t, J = 3.3Hz, 2-CH2), 4.12(1H, d, J = 2.4Hz, 5-CH), 4.32(1H, d, J = 6.6Hz, 6-CH), 7.32-7.54(9H, m, ArH). 13C NMR (CDCl3, δ ppm): 31.51(CH2S), 36.54(CH2), 45.46(CH), 85.95(C-N), 128.81-124.49(C = C), 143.87-132.36(CHaro), 180.79(C = O). EI-MS: m/z (%) = 337(M+ 36), 203(100), 309(20), 108(34). Anal.Calcd for C19H15NOS2: C, 67.62%; H, 4.48%; N, 4.15%. Found: C, 67.78%; H, 4.53%; N, 4.32%.
(5R,8R)-spiro-{7-phenyl-6-methyl-1-aza-4-thia-bicyclo [3,3,0]-6-octene-8,3'}- benzo[b]thiophene-2'-one (7)
Brownish solid, yield: 0.32g (68%), mp: 120-122°C. IR (KBr): 1725(C = O), 1420(C-N), 678(C-S) cm-1.1H NMR (CDCl3, δ ppm): 2.14(3H, d, J = 7.2 Hz, Me), 2.50(2H, t,J = 3.0Hz 3-CH2), 2.68(2H, t,J = 3.2Hz 2-CH2), 2.84(1H, q, J = 3.6Hz,5-CH), 7.59-8.45(9H, m, ArH). 13C NMR(CDCl3, δ ppm): 32.33(CH2S), 35.43(CH2), 44.45(CH), 86.54(C-N), 124.23-122.86(C = C), 143.41-130.63(CHaro), 184.34(C = O). Anal.Calcd for C20H17NOS2: C, 68.34%; H, 4.87%; N, 3.98%. Found: C, 68.55%; H, 4.93%; N, 4.13%.
(5R,8R)-spiro-{6,7-diphenyl-1-aza-4-thia-bicyclo [3,3,0]-6-octene 8, 3'}- benzo[b]thiophene-2'-one (8)
Shiny brown powder, yield: 0.29g (63%), mp: 135-133°C. IR (KBr): 1715(C = O), 1420(C-N), 6905(C-S) cm-1. 1H NMR (CDCl3, δ ppm): 2.51(2H, t,J = 2.7Hz, 3-CH2), 2.60(2H, t, J = 3.0Hz, 2-CH2), 4.15(1H, s, 5-CH) 6.79-8.12(14H, m, ArH). 13C NMR (CDCl3, δ ppm): 34.54(CH2S), 45.43(CH2), 46.72(CH), 88.23(C-N), 127.32-126.54(C = C), 146.41-132.32(Caro), 183.54(C = O). EI-MS: m/z (%) = 413(M+ 32), 385(39), 235(100), 108(35). Anal. Calcd for C25H19NOS2: C, 72.61%; H, 4.63%; N, 3.39%. Found: C, 72.73%; H, 4.78%; N, 3.86%.
(5R,8R)-spiro-{6-ethoxycarbonyl-7-phenyl-1-aza-4-thia-bicyclo [3,3,0]-6-octene-8, 3'}-benzo[b]thiophene-2'-one (9)
Dark brown power, yield: 0.31g (69%), mp: 110-112°C. IR (KBr): 1710(C = O), 1410(C-N), 690(C-S) cm-1. 1H NMR (CDCl3, δ ppm): 1.25(3H, t, J = 2.4Hz Me), 2.61(2H, t, J = 2.9Hz 3-CH2), 2.69(2H, t, J = 3.1Hz, 2-CH2), 2.67(2H, t, CH2), 3.75(2H, q, J = 6.3Hz, OCH2),4.12 (1H. s,5-CH) 7.49-7.94(4H, m, ArH). 13C NMR (CDCl3, δ ppm): 33.85(CH2), 44.96(CH), 46.32(CH2), 84.36(C-N), 124.32-122.93(C = C), 140.14-130.12(CHaro), 180.25(O = C-O), 185.44(C = O). EI-MS: m/z (%) = 321(M+ 38), 275(100), 261(20), 284(15), 234(18). Anal. Calcd for C22H19NO3S2: C, 64.52%; H, 4.68%; N, 3.42%. Found: C, 64.68%; H, 4.79%; N, 3.54%.