7-[4-(2-butoxyethoxy)phenyl]-1-isobutyl-N-[4-[(4-propyl-1H-1,2,4-triazol-5-on-3-yl)methylthio]phenyl]-2,3-dihydro-1H-1-benzazepine-4-carboxamide (0.50 g) was dissolved in dichloromethane (30 ml), and the mixture was cooled to −78° C. To the solution, 3-chloroperbenzoic acid (0.22 g) in dichloromethane solution (5 ml) was added dropwise. The mixture was stirred for 1 hour at −78° C., and then, sodium thiosulfate solution was added to the mixture. The mixture was concentrated, and extracted with ethyl acetate. The organic layer was washed with sodium bicarbonate solution, water and saturated brine, and dried over anhydrous magnesium sulfate, and then, the solvent was distilled off. The residue was purified by silica gel column chromatography (elution solvent: triethylamine/methanol/ethyl acetate), to give 7-[4-(2-butoxyethoxy)phenyl]-1-isobutyl-N-[4-[(4-propyl-1H-1,2,4-triazol-5-on-3-yl)methylsulfinyl]phenyl]-2,3-dihydro-1H-1-benzazepine-4-carboxamide (Compound 66) (0.45 g) as yellow amorphous.
