Reaction Steps
To a solution of tert-butyl 9,10-dichloro-1,4,5,6-tetrahydroazepino[4,5-b]indole-3(2H)-carboxylate (0.10 g; 0.28 mmol) in DMF (2 mL), sodium hydride (60% dispersion in mineral oil, 17 mg, 0.42 mmol) was added. After 15 min, ethyl bromoacetate (0.060 mL, 0.56 mmol) was added. The reaction was quenched with saturated aqueous NH4Cl after 2.5 h and extracted with EtOAc (3×15 mL). The combined organic extracts were washed with brine, dried over Na2SO4, decanted, and concentrated. The crude product was purified by column chromatography (Biotage, 40S) with heptane/EtOAc (3:1) to give 85 mg (70%) of a white solid: mp 136.5-138.0° C.; 1H NMR (300 MHz, CDCl3) δ 7.19 (d, J=8.7 Hz, 1H), 6.99 (d, J=8.7 Hz, 1H), 4.74 (s, 2H), 4.21 (dd, J=7.1, 7.1 Hz, 2H), 3.75 (m, 4H), 3.53 (m, 2H), 2.93 (m, 2H), 1.48 (s, 9H), 1.26 (t, J=7.1 Hz, 3H); IR (diffuse reflectance) 2985, 2976, 1737, 1685, 1466, 1450, 1414, 1367, 1344, 1249, 1213, 1169, 1156, 1115, 926 cm−1; MS (EI) m/z 440 (M+), 307, 305, 301, 299, 298, 272, 225, 189, 58, 56; Anal. Calcd for C21H26Cl2N2O4: C, 57.15; H, 5.94; N, 6.35; found: C, 57.16; H, 5.98; N, 6.27.
