A solution of 1,1-dimethylethyl 2-(aminomethyl)-1-pyrrolidinecarboxylate (1000 mg, 5 mmol) and methyl 4-formylbenzoate (820 mg, 5 mmol) in dichloroethane was stirred as acetic acid (450 mg, 7.5 mmol) and sodium triacetoxyborohydride (1271 mg, 6 mmol) were added sequentially at ambient temperature. After stirring at ambient temperature for 17 hours, treated with a saturated aqueous solution of sodium bicarbonate and extracted with EtOAc. The combined organic extracts were dried and concentrated. Purification by flash chromatography afforded 1,1-dimethylethyl 2-[[[[4-(methoxycarbonyl)phenyl]methyl]amino]methyl]-1-pyrrolidinecarboxylate (800 mg), 1H NMR (CDCl3) 7.98 (d, 2H), 3.37 (d, 2H), 3.91 (s, 3H), 3.82 (s, 2H), 3.36 (m, 2H), 2.72 (m, 1H), 1.82 (m, 3H), 1.44 (m, 2H) ppm.
