General procedure for the synthesis of N-Benzyloxycarbonyl-4-piperidinesulfonyl chloride from benzyl 4-(acetylthio)piperidine-1-carboxylate: Benzyl 4-(acetylthio)piperidine-1-carboxylate (1.45 g, 4.94 mmol) was dissolved in a mixed solvent of dichloromethane (10 mL) and water (40 mL), and the reaction was stirred for 4 hours at 0 °C, while chlorine was passed through the reaction. After completion of the reaction, the organic layer was separated and the aqueous layer was extracted with dichloromethane. The organic layers were combined, dried with anhydrous magnesium sulfate, and concentrated under reduced pressure to remove the solvent to afford benzyl 4-(chlorosulfonyl)-1-piperidinecarboxylate (1.58 g, 100% yield).
