To a dichloromethane (80 mL) solution of the (R)-3-amino-1-(4-chlorobenzyl)pyrrolidine (3.35 g, 16 mmol), were added triethylamine (2.5 mL, 17.6 mmol), N-tert-butoxycarbonylglycine (2.79 g, 16.0 mmol), EDCI (3.07 g, 16.0 mmol) and HOBt (12.16 g, 16 mmol). The resulting reaction mixture was stirred at 25° C. for 16 hours, and a 2 M solution (80 mL) of NaOH was then added thereto. The organic layer was separated, and the aqueous layer was extracted with dichloromethane (100 mL×3). The organic layers were combined, washed with water (100 mL×2) and brine (100 mL), dried over anhydrous sodium sulfate, filtered, concentrated and purified by column chromatography (SiO2, ethyl acetate) to thereby provide the objective (R)-3-[N-(tert-butoxycarbonyl)glycyl]amino-1-(4-chlorobenzyl)pyrrolidine (5.40 g, 92%).
