Diethyl Oxalate → 3,4,4a,5,6,7-Hexahydropyrazino[1,2-a][1]benzazepine-1,2-dione

Participants

Reaction Steps

A solution of Example 182E (0.282 g, 1.600 mmol) in diethyl oxalate (1.518 mL, 11.20 mmol) was heated at 140° C. for 1 hour and then at 180° C. for 2 hours. The crude mixture was purified by silica gel chromatography (Analogix IntelliFlash™ 280, SF24-40) eluting with dichloromethane, then with 2% methanol/dichloromethane, and then with 10% methanol/dichloromethane to obtain the title compound. 1H NMR (400 MHz, DMSO-d6) δ ppm 8.66 (s, 1H), 7.37-7.17 (m, 4H), 3.91 (dd, J=12.8, 4.2, 1H), 3.49 (d, J=11.4, 1H), 3.19-3.13 (m, 1H), 2.71 (dd, J=18.6, 12.5, 1H), 2.56 (m, 1H), 2.02 (m, 2H), 1.86 (m, 1H), 1.42 (m, 1H); MS (ESI+) m/z 248.2 (M+NH4)+.

Provenance & Evidence