Methyl 2-cyano-5,6-dihydrobenzo[f]imidazo[1,2-d][1,4]oxazepine-9-carboxylate (0.46 g, 1.7 mmol) was stirred with potassium carbonate (469 mg, 3.4 mmol), water (1.2 mL) and hydrogen peroxide (408 mg, 6 mmol) in DMSO (7 mL) for 4 hours. The mixture was diluted with 70 mL of water and extracted with ethyl acetate. Ethyl acetate solution was washed with water, 5% Na2S2O3, water, brine, dried over MgSO4 and concentrated under vacuum to give methyl 2-carbamoyl-5,6-dihydrobenzo[f]imidazo[1,2-d][1,4]oxazepine-9-carboxylate (0.37 g).
