(S)-tert-butyl 3-(hydroxymethyl)piperidine-1-carboxylate (3.5 g, 16.59 mmol) was dissolved in CH2Cl2 (60 ml), and then TsCl (3.8 g, 19.91 mmol), Et3N (3.47 ml, 24.87 mmol), and DMAP (0.21 g, 1.66 mmol) were added, followed by at room temperature for 3 hours. After the completion of the reaction, the reaction mixture was extracted with H2O, MC, and brine, followed by drying (Na2SO4), filtration, and concentration under reduced pressure, and the residue was purified by column chromatography (EA:Hex=1:5), to give (S)-tert-butyl 3-((tosyloxy)methyl)piperidine-1-carboxylate (6 g, 97%).
