To a solution of 5-[(2,5-difluorophenyl) [(4-fluorophenyl)thio]methyl]-4-meth ylpyridine-2-carboxylic acid (483 mg, 1.24 mmol) obtained in Example 20 in methylene chloride (10 ml), 2-aminoethanol (0.083 ml, 1.36 mmol), 1-hydroxybenzotriazole (184 mg, 1.36 mmol), 4-methylmorpholine (0.150 ml, 1.36 mmol), and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (262 mg, 1.36 mmol) were added at room temperature. After stirring for 4 hours at room temperature, water was added to the reaction mixture, and the mixture was washed with saturated aqueous ammonium chloride. The organic layer was dried over anhydrous sodium sulfate and filtered, then the filtrate was concentrated under reduced pressure, and the obtained residue was subjected to flash silica gel chromatography. The fraction obtained from an elution with hexane:ethyl acetate=1:3 was concentrated under reduced pressure, to obtain the title compound (481 mg, 1.11 mmol, 90%) as a colorless foamy substance.
