8 mg of 2,6-difluorophenol and 8 mg of potassium carbonate were added to an N-methylpyrrolidinone (0.5 ml) solution of 8.6 mg of N-(2,3-difluoro-4-(6-methanesulfonyl-pyridin-3-yloxy)-6-nitro-phenyl)pyrazinecarboxamide, and the reaction liquid was stirred at 90° C. for 15 minutes. 75 mg of tin(II) chloride dihydrate was added to it, and the reaction liquid was stirred overnight at 90° C. Further, 3 mg of p-toluenesulfonic acid was added to it, and the reaction liquid was stirred at 90° C. for 2 hours. The deposit was taken out through filtration, and purified through reversed-phase middle-pressure liquid chromatography [ODS-AS-360-CC (by YMC), mobile phase: water-acetonitrile-0.1% trifluoroacetic acid]. The solvent of the resulting fraction was diluted with ethyl acetate, washed with aqueous saturated sodium bicarbonate, and dried with anhydrous sodium sulfate. The solvent was evaporated away under reduced pressure to obtain the entitled compound as a brown solid.
