A mixture of 3,5-dichloro-6-ethylpyrazine-2-carboxamide (420 mg), 4-[(2S)-2,4-dimethylpiperazin-1-yl]aniline (392 mg), diisopropylethylamine (665 μL), and dioxane (8.4 mL) was stirred at 110° C. overnight. To the reaction mixture was added water, followed by extraction with ethyl acetate. The organic phase was washed with saturated brine and dried over anhydrous magnesium sulfate, and then the solvent was evaporated under reduced pressure. The obtained residue was purified by silica gel column chromatography (eluent; chloroform:methanol=95:5) to obtain 5-chloro-3-({4-[(2S)-2,4-dimethylpiperazin-1-yl]phenyl}amino)-6-ethylpyrazine-2-carboxamide (560 mg) as a brown solid.
