In a stream of nitrogen and at 0° C., 0.15 ml (1.10 mmol) of hexanoyl chloride was added to an anhydrous tetrahydrofuran (10 ml) solution containing 400 mg (1.00 mmol) of 3-(4-methoxybenzyloxy)-N-(2-sulfamoylphenyl)benzamide produced in Reference Example 6 and 237 mg (1.90 mmol) of 4-dimethylaminopyridine, the mixture was stirred at room temperature for 1 hour and then the solvent was evaporated under a reduced pressure. The resulting residue was dissolved in ethyl acetate, washed with water, a potassium hydrgensulfate aqueous solution and saturated brine in that order and dried over anhydrous sodium sulfate, and then the solvent was evaporated under a reduced pressure. The resulting residue was purified by a silica gel column chromatography to obtain 490 mg (yield: 98.8%) of the title compound.
