A solution of 250 mg (0.74 mmol) of (RS)-4-amino-1-[4-(3-fluoro-benzyloxy)-phenyl]-pyrrolidin-2-one hydrochloride [Example 1f)] in 12 ml of dichloromethane is cooled to 0° C. and successively treated with 226 μl (1.6 mmol) of triethylamine and 64 μl (0.8 mmol) of methyl chloroformate. The mixture is left to warm to RT and stirred for 1 hour. For the working-up, dichloromethane and water are added to the reaction mixture. The organic layer is separated, dried over sodium sulfate, and evaporated. There are obtained 203 mg (76% of theory) of (RS)-{1-[4-(3-fluoro-benzyloxy)-phenyl]-5-oxo-pyrrolidin-3-yl}-carbamic acid methyl ester as a white solid. MS: m/e=359 (M+H)+.
