A mixture of benzyl 2-(4-bromo-3-fluorophenyl)pyrrolidine-1-carboxylate (15.3 g, 40.6 mmol), 1,1′-bis(diphenylphosphino)ferrocene palladium (II) dichloride (1.67 g, 2.0 mmol) and triethylamine (8.4 mL, 60.9 mmol) in methanol (180 mL) was stirred under 60 psi of carbon monoxide at 100° C. for 4 hour. After cooling to ambient temperature, the mixture was concentrated and the residue purified by flash chromatograph on silica gel using a gradient of 8-15% ethyl acetate in petroleum ether to give benzyl 2-(3-fluoro-4-(methoxycarbonyl)phenyl)pyrrolidine-1-carboxylate as colorless oil (8.71 g, yield 60%). LC-MS (ESI) m/z: 358 (M+1)+.
