3-chloroperbenzoic acid (3.91 g, 22.7 mmol) was added to a methylene chloride (9 mL) solution of 3-(5-isopropyl-2,4-bis-methoxymethoxyphenyl)-4-[4-(4-methylpiperazin-1-ylmethyl)phenyl]-5-methylsulfanyl-[1,2,4]triazole (F652-07, 2.05 g, 3.78 mmol). After stirring at room temperature for 9.5 hours, additional 3-chloroperbenzoic acid (717 mg, 4.15 mmol) was added and stirring was continued overnight. After cooling to ice cold, saturated aqueous sodium thiosulfate and then 10% aqueous potassium bisulfite were added, and stirring was continued for a while. Further, saturated aqueous sodium hydrogencarbonate was added and the mixture was stirred, and then extracted with chloroform. The extract was washed sequentially with saturated aqueous sodium hydrogencarbonate, water and saturated sodium chloride solution, and dried over anhydrous sodium sulfate. Filtration and evaporation gave pale brown foam. After adding diethyl ether, the insoluble solids were removed by filtration, and the solvent in the filtrate was distilled off under reduced pressure. The solids thus obtained were purified by silica gel column chromatography (chloroform, methanol) to obtain 3-(5-isopropyl-2,4-bis-methoxymethoxyphenyl)-4-[4-(4-methylpiperazin-1-ylmethyl)phenyl]-5-methanesulfonyl-[1,2,4]triazole (F652-08, pale yellow foam, 1.08 g, 50%).
