Aluminium lithium hydride → tert-butyl N-[2-(3,5-difluorophenyl)-1-oxopropan-2-yl]carbamate

To a stirred solution of tert-butyl 2-[(tert-butoxycarbonyl)amino]-2-(3,5-difluorophenyl)propanoate (27.0 g, 76 mmol) in THF (350 mL) at −78° C. was added LiAlH4 (76 mL of a 1 M solution in THF, 76 mmol), dropwise. The reaction mixture was stirred at −78° C. for 3 h, then quenched with EtOAc (76 mL), then H2O (228 mL), then 1 N aqueous NaOH (76 mL), then EtOAc (228 mL). The reaction mixture was warmed to ambient temperature, stirred for 1 h, filtered, and extracted with EtOAc (2×450 mL). The organic extracts were dried over Na2SO4, filtered, and concentrated in vacuo. The crude product was purified by silica gel chromatography, eluting with hexane:EtOAc—100:0 to 70:30, to give the title compound. MS: m/z=186 (M−CO2C4H7).