A solution of (R)-3-amino-1-(4-chlorobenzyl)pyrrolidine (3.35 g, 16 mmol) in CH2Cl2 (80 mL) was treated with Et3N (2.5 mL, 17.6 mmol), N-tert-butoxycarbonylglycine (2.79 g, 16.0 mmol), EDCI (3.07 g, 16.0 mmol) and HOBt (2.16 g, 16 mmol). After the reaction mixture was, stirred at 25° C. for 16 h, 2 N NaOH solution (80 mL) was added. The organic layer was separated, and the aqueous layer was extracted with dichloromethane (100 mL×3). The combined organic layer was washed with water (100 mL×2) and brine (100 mL), dried over anhydrous sodium sulfate, filtered, and concentrated. Column chromatography (SiO2, ethyl acetate) afforded the desired (R)-3-(N-(tert-butoxycarbonyl)glycyl)amino-1-(4-chlorobenzyl)pyrrolidine (5.40 g, 92%).
