To a solution of N-{1-[3,5-bis(trifluoromethyl)phenyl]ethyl}-N-({2-[(cyclopentylmethyl)(ethyl)amino]-5-(trifluoromethyl)phenyl}methyl)-5-[2-(methylthio)ethoxy]pyrimidin-2-amine (348 mg, 0.49 mmol) obtained in Example 1 in acetonitrile (7 mL) was added molybdenum dioxide dichloride (14.6 mg, 0.073 mmol) and 30% aqueous hydrogen peroxide (220 mg, 1.94 mmol), and the mixture was stirred at room temperature for 23 hours. The reaction mixture was added with saturated aqueous sodium sulfite, and extracted with chloroform. Then, the organic layer was washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The resulting residue was purified by preparative silica gel thin layer chromatography (hexane:acetone=2:1) to obtain N-{1-[3,5-bis(trifluoromethyl)phenyl]ethyl}-N-({2-[(cyclopentylmethyl)(ethyl)amino]-5-(trifluoromethyl)phenyl}methyl)-5-[2-(methylsulfinyl)ethoxy]pyrimidin-2-amine (compound of Example 2, 32.8 mg, 9%) as yellow oil, and N-{1-[3,5-bis(trifluoromethyl)phenyl]ethyl}-N-({2-[(cyclopentylmethyl)(ethyl)amino]-5-(trifluoromethyl)phenyl}methyl)-5-[2-(methylsulfonyl)ethoxy]pyrimidin-2-amine (compound of Example 3, 295 mg, 81%) as a pale yellow oil.
