To a mixture of 1-(4-methoxybenzyl)-3-methyl-3-(3,4,5-trifluorophenoxy)piperidin-2-one (76.2 mg) in acetonitrile (1 mL) was added a mixture of cerium(IV) ammonium nitrate (275 mg) in water (1 mL) at room temperature, and the mixture was stirred overnight. Cerium(IV) ammonium nitrate (110 mg) was added, and the mixture was stirred at room temperature for 1 hr. The reaction mixture was diluted with ethyl acetate and saturated aqueous sodium hydrogen carbonate solution, and the insoluble material was removed by filtration. 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 (NH, ethyl acetate) and silica gel column chromatography (ethyl acetate/hexane) to give the title compound (30.1 mg).
