[Synthesis]
GENERAL STEPS: To a solution of nicotinic acid (0.5 mmol), triethylamine (1.2 mmol), HOBT (0.6 mmol) and EDCI (0.6 mmol) in dichloromethane (8 mL) was added tryptamine (0.5 mmol). The reaction mixture was stirred at room temperature overnight, followed by evaporation under reduced pressure to remove the dichloromethane. The residue was dissolved in ethyl acetate (10 mL) and washed sequentially with 10% aqueous sodium bicarbonate (3 x 10 mL) and water (10 mL). The organic phase was dried over anhydrous sodium sulfate and concentrated to dryness under reduced pressure. The residue was purified by silica gel column chromatography using a solvent mixture of dichloromethane/methanol as eluent to give the pure solid product N-(2-(1H-indol-3-yl)ethyl)nicotinamide (4a). White solid; 72% yield; 1H NMR (500 MHz, DMSO-d6) δ 10.84 (s, 1H), 9.02 (d, J = 1.3 Hz, 1H), 8.82 (t, J = 5.0 Hz, 1H), 8.72 (dd, J = 4.6, 1.3 Hz, 1H), 8.20 (d, J = 7.9 Hz, 1H), 7.60 (d, J = 7.8 Hz, 1H), 7.52 (dd, J = 7.6, 5.1 Hz, 1H), 7.37 (d, J = 8.1 Hz, 1H), 7.21 (s, 1H), 7.09 (t, J = 7.5 Hz, 1H), 7.00 (t, J = 7.4 Hz, 1H), 3.59 (dd, J = 13.6, 6.9 Hz, 2H ), 3.00 (t, J = 7.4 Hz, 2H). |