To a mixture of 4-phenyl-1-pyrrolidin-3-yl-piperidine dihydrochloride (preparation #7) (3.0 g, 9.90 mmol), tert-butoxycarbonylamino-acetic acid (1.73 g, 9.90 mmol) and EDC (1.90, 9.90 mmol) in DCM (60 mL) was added Et3N (5.5 mL, 39.6 mmol). The reaction mixture was stirred at ambient temperature for about 16 h. DCM was added and the organic layer was washed with water and saturated NaHCO3, dried over MgSO4, filtered and concentrated in vacuo. The crude product was purified by silica gel chromatography using 5% MeOH/EtOAc as the mobile phase to afford {2-oxo-2-[3-(4-phenyl-piperidin-1-yl)-pyrrolidin-1-yl]-ethyl}-carbamic acid tert-butyl ester (1.47 g, 38% yield). RP-HPLC (Table 1, Method b) Rt 1.54 min; m/z: (M+H)+ 388.
