To a solution of tert-butyl ({4-fluoro-5-(2-fluoropyridin-3-yl)-1-[(2-methylpyridin-3-yl)sulfonyl]-1H-pyrrol-3-yl}methyl)methylcarbamate (288 mg) in ethyl acetate (2 mL) and 2-propanol (1 mL) was added 4 mol/L hydrogen chloride-ethyl acetate solution (3 mL), and the mixture was stirred at room temperature for 3 hr. The reaction mixture was concentrated under reduced pressure, and the residue was diluted with saturated aqueous sodium hydrogen carbonate solution, and extracted with ethyl acetate. The separated aqueous layer was extracted again with ethyl acetate. Combined organic layers were washed with saturated brine, dried over anhydrous magnesium sulfate and concentrated under reduced pressure to give 1-{4-fluoro-5-(2-fluoropyridin-3-yl)-1-[(2-methylpyridin-3-yl)sulfonyl]-1H-pyrrol-3-yl}-N-methylmethanamine as a colorless oil (yield 220 mg, 97%). A solution of the obtained 1-{4-fluoro-5-(2-fluoropyridin-3-yl)-1-[(2-methylpyridin-3-yl)sulfonyl]-1H-pyrrol-3-yl}-N-methylmethanamine in ethyl acetate (3 mL) was added dropwise to a solution of fumaric acid (67 mg) in ethanol (3 mL) and concentrated under reduced pressure. The residue was recrystallized from ethanol to give the title compound as a white solid (yield 253 mg, 88%).
