General procedure for the synthesis of 4-methylsulfonylpiperidine from tert-butyl 4-(methylsulfonyl)piperidine-1-carboxylate (Step 4): tert-butyl 4-(methylsulfonyl)piperidine-1-carboxylate obtained in Step 3 of Reference Example 12 was dissolved in ethyl acetate (16 mL), followed by the addition of a 4.0 mol/L dioxane solution of hydrogen chloride (12 mL). The reaction mixture was stirred at room temperature for 3 hours. Upon completion of the reaction, the precipitated solid was collected by filtration to afford the target product 4-(methylsulfonyl)piperidine (1.4 g, 76% yield). The structure of the product was confirmed by 1H-NMR (DMSO-d6, 270 MHz) with the following chemical shifts δ (ppm): 3.41-3.31 (m, 3H), 2.97 (s, 3H), 2.97-2.82 (m, 2H), 2.18-2.13 (m, 2H), 1.92-1.73 (m, 2H).
