Trifluoroacetic anhydride → HCID 57749303, compound

A mixture of N-{5-[(1-(2-amino-2-oxoethyl)-6-{[(4-methylphenyl)sulfonyl]amino}-1,6-dihydropyridin-3-yl)oxy]-2-fluorophenyl}-1,3-dimethyl-1H-pyrazole-5-carboxamide (5.85 g, 10.6 mmol), trifluoroacetic anhydride (40 mL) and dichloromethane (40 mL) was stirred at room temperature for 6 hr. The reaction solution was concentrated under reduced pressure, ethyl acetate (50 mL) and saturated aqueous sodium hydrogen carbonate solution (50 mL) were added to the residue and the mixture was stirred for 10 min. The organic layer was washed with saturated brine, dried over anhydrous magnesium sulfate and filtrated. The filtrate was concentrated under reduced pressure, 8N aqueous sodium hydroxide solution (15 mL) and ethanol (60 mL) were added to the residue. The mixture was stirred at room temperature for 2 hr and at 60° C. for 2 hr. The reaction mixture was diluted with water and extracted with ethyl acetate/tetrahydrofuran (×3). The organic layer was washed with saturated brine, dried over anhydrous magnesium sulfate and filtrated. The filtrate was concentrated under reduced pressure, and the residue was purified by column chromatography (NH silica gel, ethyl acetate) and recrystallized from ethyl acetate-hexane to give the title compound (730 mg, 18%) as a white solid.