To a solution of tert-butyl (1-{4-[2-(4-nitrophenyl)-9H-imidazo[1,2-d]pyrido[2,3-b][1,4]benzodiazepin-3-yl]phenyl}cyclobutyl)carbamate (317 mg, 0.49 mmol) in THF (10 mL) and MeOH (5 mL) cooled to 0° C. was added NiCl2 (245 mg, 1.03 mmol) and NaBH4 (84 mg, 2.04 mmol). The reaction was slowly allowed to warm to room temperature and stirred 30 min. The reaction was diluted with sat.NaHCO3aq and extracted with ethyl acetate (3×20 mL). The organic layers were combined, washed with brine. The organic phase was dried over sodium sulfate, filtered and concentrated gave the title compound as a yellow solid (214 mg, 76%).
