287954-99-8

622386-94-1

To the methanesulfonamide in Part A was added dichloromethane (300 mL) and triethylsilane (125 mL, 778 mmol). Trifluoroacetic acid (300 mL, 3.9 mol) was added to the suspension. The resulting mixture was stirred at ambient temperature for 1 hr while keeping the reaction vessel sealed, followed by vacuum concentration to give a solid product. The solid was mixed with methanol (150 mL) in a sealed flask at ambient temperature for 2 days. Afterwards, the solid was separated from the suspension by filtration and washed with additional methanol (100 mL). The resulting solid was dried in a vacuum oven at 50 °C overnight to yield 54.14 g (91.7% yield) of the target product 4-(4-bromophenyl)-1-(methylsulfonyl)piperidine. The structure of the product was confirmed by 1H NMR analysis.