Reaction Steps
To a solution of compound 6 (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. The reaction was added sat. NaHCO3 solution (5 mL) 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 (10:90) afforded 0.102 g (60%) of compound 6a as an off-white solid. IR (KBr) νmax. cm−1: 3436 (NH), 3052 (Ar—H), 2953 (Alph-H), 1702 (C═O), 1614, 1515, 1425 (C═C), 1229 (C—N), 1162 (C—O). 1H NMR (500 MHz, DMSO-d6) δ=2.76 (m, 4H, 2CH2), 3.18 (m, 4H, 2CH2), 3.67 (s, 2H, CH2), 4.49 (s, 2H, CH2), 6.60 (d, 1H, J=2.3 Hz, aromatic H), 6.70 (dd, 1H, J=2.2, 8.5 Hz, aromatic H), 7.43-7.48 (m, 6H, aromatic H), 7.58-7.62 (m, 4H, aromatic H). 13C NMR (125.7 MHz, DMSO-d6) δ=43.70 (CH2), 48.23 (CH2), 53.03 (CH2), 62.64 (CH2), 114.56 (aromatic-C), 117.64 (aromatic-C), 119.82 (aromatic-C), 124.58 (aromatic-C), 127.19 (aromatic-C), 127.26 (aromatic-C), 127.55 (aromatic-C), 127.90 (aromatic-C), 128.95 (aromatic-C), 129.26 (aromatic-C), 130.25 (aromatic-C), 130.59 (aromatic-C), 136.66 (aromatic-C), 138.22 (aromatic-C), 138.66 (aromatic-C), 140.95 (aromatic-C), 146.88 (aromatic-C), 156.32 (C═O). Calculated (%) for C25H26N4O (398.21); C, 75.35; H, 6.58; N, 14.06. found (%); C, 75.27; H, 6.65; N, 13.96.
