To a methylene chloride (10 ml) solution of the [5-chloro-4-[(4-chlorophenylsulfonyl)(2,5-difluorophenyl)methyl]pyridin-2-yl]amine (331 mg, 0.771 mmol) obtained in Example 196 and pyridine (94 μl, 1.16 mmol) was added a methylene chloride (2 ml) solution of ethyl chlorosulfonylacetate (216 mg, 1.16 mmol) at 0° C. After the resulting mixture was stirred at room temperature for 12 hours, pyridine (94 up, 1.16 mmol) and a methylene chloride (2 ml) solution of ethyl chlorosulfonylacetate (216 mg, 1.16 mmol) were added sequentially at 0° C. The resulting mixture was stirred at room temperature for 9 hours and then, the reaction mixture was concentrated under reduced pressure. To the residue thus obtained was added ethyl acetate. The resulting mixture was washed sequentially with a saturated aqueous solution of sodium bicarbonate and brine, dried over anhydrous sodium sulfate, and filtered. The filtrate was concentrated under reduced pressure. The residue thus obtained was subjected to flash silica gel column chromatography. The fraction obtained from the hexane:ethyl acetate (=3:1) eluate was concentrated under reduced pressure to give the title compound (239 mg, 0.412 mmol, 53%) as a white solid.
