To a solution of 1-(bromomethyl)-2,4-bis(trifluoromethyl)benzene (89 g) in N,N-dimethylformamide (1 L) were added 4-piperidinemethanol (50 g) and potassium carbonate (60.0 g), and the mixture was stirred at room temperature for 2 hr. Water/ethyl acetate were added to the reaction mixture, and the organic layer was separated, washed with water and saturated brine, and dried over anhydrous magnesium sulfate, and the solvent was evaporated under reduced pressure. To a solution of the obtained oil and triethylamine (242 mL) in dimethyl sulfoxide (1 L) was added sulfur trioxide pyridine complex (138 g), and the mixture was stirred at room temperature for 1 hr. Water/ethyl acetate were added to the reaction mixture, and the organic layer was separated, washed with water and saturated brine, and dried over anhydrous magnesium sulfate, and the solvent was evaporated under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate/hexane) to give the title compound (85 g).
