General procedure for the synthesis of N-Benzyloxycarbonyl-3-hydroxypiperidine from 3-hydroxypiperidine hydrochloride and benzyl chloroformate: Na2CO3 (23.10 g, 218 mmol) was added to a solution of THF/H2O (50 mL/50 mL) containing 3-hydroxypiperidine hydrochloride (10.00 g, 73 mmol). Benzyl chloroformate (14.90 g, 87 mmol) was added dropwise at room temperature and the reaction mixture was stirred for 5 hours. After the reaction was completed, the mixture was extracted with EtOAc (100 mL x 3). The organic layers were combined, washed with brine, dried over anhydrous magnesium sulfate, filtered and concentrated. The resulting residue was purified by silica gel column chromatography with EtOAc/petroleum ether (1/100~1/4, v/v) as eluent to afford N-benzyloxycarbonyl-3-hydroxypiperidine (16.50 g, 96%) as a colorless oil. detected by TLC: Rf = 0.65 (silica gel plate, EtOAc/petroleum ether = 1/1, v/v).
