To a tetrahydrofuran (5 ml) solution of ethyl[[[5-chloro-4-[(4-chlorophenylsulfonyl)(2,5-difluorophenyl)methyl]pyridin-2-yl]amino]sulfonyl]acetate (67 mg, 0.116 mmol) was added an ether solution (0.18 ml) of 1M lithium aluminum hydride at 0° C. The resulting mixture was stirred at 0° C. After the termination of the reaction was confirmed by TLC, a saturated aqueous solution of ammonium chloride was added to the reaction mixture. The resulting mixture was filtered through Celite. The filtrate was 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 (=2:1) eluate was concentrated under reduced pressure to give the title compound (39 mg, 0.073 mmol, 63%) as a white solid.
