235 mg of (S)-6-chloro-N-[1-(4-fluorophenyl)ethyl]-4-(1-methyl-1H-pyrazol-4-yl)pyridine-2-amine, 74 mg of 2-aminopyrazine, 68 mg of 2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl, 95 mg of sodium t-butoxide and 37 mg of tris(dibenzylideneacetone)(chloroform)dipalladium were added in turn to 6 ml of degassed toluene, and the mixture was stirred at 100° C. for 1.5 hours under argon atmosphere. The reaction solution was diluted with ethyl acetate. The solution was washed in turn with water and brine and then dried over magnesium sulfate. The solvent was distilled off under reduced pressure, and then the obtained residue was purified by silica gel column chromatography to obtain 204 mg of (S)—N2-[1-(4-fluorophenyl)ethyl]-4-(1-methyl-1H-pyrazol-4-yl)-N6-(pyrazin-2-yl)pyridine-2,6-diamine as pale yellow powder. The obtained compound was dissolved in ethanol, and an equivalent of 1N hydrochloric acid was added thereto, and then the solvent was removed to obtain the objective compound as pale yellow powder.
