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 (12.16 g, 16 mmol) were added to the CH2Cl2 (80 mL) solution of the (R)-3-amino-1-(4-chlorobenzyl)pyrrolidine (3.35 g, 16 mmol). The reaction mixture was stirred at 25° C. for 16 hours, and then mixed with a 2M NaOH solution (80 mL). The organic layer was separated, and the aqueous layer was extracted with dichloromethane (100 mL×3). The obtained organic layers were combined, washed with water (100 mL×2) and aqueous sodium chloride solution (100 mL), dried over anhydrous sodium sulfate, filtered and then concentrated. The objective (R)-3-{N-(tert-butoxycarbonyl)glycyl}amino-1-(4-chlorobenzyl)pyrrolidine (5.40 g, 92%) was obtained by column chromatography (SiO2, ethyl acetate).
