Synthesis
To a solution of N-Boc-4-hydroxypiperidine (5 g, 24.8 mmol) in dichloromethane (50 mL) was sequentially added triethylamine (13.9 mL, 99.4 mmol) and p-toluenesulfonyl chloride (9.47 g, 49.7 mmol). The reaction mixture was stirred at room temperature for 20 hours. Upon completion of the reaction, the solution was concentrated in vacuum. The residue was redissolved in a mixture of dichloromethane (20 mL) and water (20 mL) and the organic layer was extracted with dichloromethane (20 mL). Subsequently, the organic layer was washed with 1N HCl (40 mL) and extracted twice more with dichloromethane (2 x 40 mL). The organic layers were combined, dried with anhydrous magnesium sulfate, filtered and concentrated. Finally, the crude product was purified by silica gel column chromatography (petroleum ether/ethyl acetate, 8:2) to afford tert-butyl 4-(toluene-4-sulfonyloxy)piperidine-1-carboxylate (8.7 g, quantitative yield) as a white crystalline solid.
References
[1] Patent: WO2018/50771, 2018, A1. Location in patent: Page/Page column 72
[2] Patent: WO2007/102883, 2007, A2. Location in patent: Page/Page column 36-37
[3] Patent: WO2013/170072, 2013, A2. Location in patent: Paragraph 001074
[4] Patent: WO2007/30366, 2007, A1. Location in patent: Page/Page column 135
[5] Journal of Medicinal Chemistry, 2012, vol. 55, # 22, p. 9958 - 9972
