Reaction Steps
Representative procedure: To a solution of compound 5 (0.15 g, 0.43 mmol) and biphenyl-4-carbaldehyde (a) (0.1 g, 0.55 mmol) in DMSO (2 mL) at 0° C. was added Et3N (0.13 mL, 0.97 mmol). After being stirred for 0.5 h at room temperature, NaBH(OAc)3 (0.11 g, 0.53 mmol) was added, and the mixture was stirred for 6 h. Sat. NaHCO3 solution (5 mL) was added and stirred for 15 min, followed by the addition of ethyl acetate (20 mL). The organic layer was separated and washed with sat. NaHCO3, brine, and dried over Na2SO4 and evaporated. Column chromatography on silica gel, eluting with methanol:dichloromethane (5:95) and then changing to 10:90 afforded 0.099 g (58%) of compound 5a as an off-white solid, m.p. 134-135° C.; IR (KBr) νmax. cm−1: 3431 (NH), 3062 (Ar—H), 2963 (Alph-H), 1703 (C═O), 1620, 1512, 1430 (C═C), 1221 (C—N), 1168 (C—O). 1H NMR (500 MHz, DMSO-d6) δ=2.71 (m, 4H, 2CH2); 3.14 (m, 4H, 2CH2); 3.68 (s, 2H, CH2); 4.47 (s, 2H, CH2); 6.64 (d, 1H, J=2.3 Hz, aromatic H); 6.68 (d, 1H, J=8.3 Hz, aromatic H); 6.78 (dd, 1H, J=2.2, 8.4 Hz, aromatic H); 7.43-7.48 (m, 5H, aromatic H); 7.58-7.61 (m, 4H, aromatic H); 13C NMR (125.7 MHz, DMSO-d6) δ=43.78 (CH2), 50.11 (CH2), 53.02 (CH2), 62.69 (CH2), 98.21 (aromatic-C), 114.64 (aromatic-C), 115.15 (aromatic-C), 117.28 (aromatic-C), 118.25 (aromatic-C), 127.18 (aromatic-C), 127.28 (aromatic-C), 127.53 (aromatic-C), 127.91 (aromatic-C), 128.97 (aromatic-C), 129.21 (aromatic-C), 130.29 (aromatic-C), 130.57 (aromatic-C), 140.92 (aromatic-C), 147.12 (aromatic-C), 156.34 (C═O). Calculated (%) for C25H26N4O (398.21); C: 75.35, H: 6.58, N: 14.06. found (%); C: 75.28, H: 6.64, N: 13.97.
