To a mixture of 3-(2-cyanopropan-2-yl)-N-(2,4-difluoro-5-nitrophenyl)benzamide 72 (155 mg, 0.449 mmol) and zinc (440 mg, 6.73 mmol) in THF (5 mL) at −5° C., acetic acid (0.514 mL, 539 mg, 8.98 mmol) was added. The reaction was stirred 30 min at −5° C. and 1 h at rt. Ethanol and acetonitrile were added and filtrated. The filtrate was diluted with CH2Cl2 and washed with saturated NaHCO3 solution to give N-(5-amino-2,4-difluorophenyl)-3-(2-cyanopropan-2-yl)benzamide 73 (100 mg, 70%). (m/z)=316 (M+H)+.
