Benzyl chloroformate → 7-Methoxy-2-oxo-1,2,3,5-tetrahydro-benzo[e][1,4]diazepine-4-carboxylic acid benzyl ester

Participants

Reaction Steps

To a solution of 4-benzyl-7-methoxy-1,3,4,5-tetrahydro-benzo[e][1,4]diazepin-2-one (4.67 g, 16.5 mmol) in dichloromethane (150 mL) was added benzyl chloroformate (6.2 g, 36.0 mmol). The mixture was heated to reflux for four hours whereupon LCMS showed completion of the reaction. The mixture was cooled to room temperature, washed with saturated aqueous sodium bicarbonate and brine, dried over magnesium sulfate, filtered and concentrated. The crude product was purified by flash chromatography over silica gel (0-5% MeOH/DCM) to afford 5.0 g (93%) of 7-methoxy-2-oxo-1,2,3,5-tetrahydro-benzo[e][1,4]diazepine-4-carboxylic acid benzyl ester; NMR (400 MHz, DMSO-d6) δ 9.96 (s, 1H), 7.35 (m, 5H), 7.04 (d, J=9 Hz, 1H), 6.84 (d, J=9 Hz, 1H), 5.08 (s, 2H), 4.54 (s, 2H), 4.20 (2s, 2H), 3.70 (2s, 3H); MS (m/e) 327 (M+1); mp 138° C.

Provenance & Evidence