p-Toluenesulfonyl chloride (0.858 g, 4.50 mmol), triethylamine (0.820 ml, 6.00 mmol) and 4-dimethylaminopyridine (0.0366 g, 0.300 mmol) were added to a solution of 2-[1-(2-fluoro-4-nitrophenyl)piperidin-4-yl]ethanol (compound of Reference Example 25; 0.804 g, 3.00 mmol) in anhydrous dichloromethane (5 ml), and the mixture was stirred at room temperature for 17 hours. Water was added to the reaction mixture and the mixture was extracted with ethyl acetate. The organic layer was washed with saturated brine and dried over anhydrous sodium sulfate. The residue obtained by evaporation of the solvent under reduced pressure was purified by column chromatography on silica gel (n-hexane:ethyl acetate=2:1) to give the title compound (0.661 g, 52%) as a yellow solid.
