m-Chloroperbenzoic acid → 4-(8-Methylimidazo[1,2-a]pyridin-3-yl)pyrimidine-5-carbonitrile

300 mg of the compound [1-6] was dissolved in 6 mL of chloroform, and 368 mg of m-chloroperbenzoic acid was added thereto under an ice-cold condition. After the 30 minutes stirring at the same temperature, to the reaction mixture was added a saturated aqueous solution of sodium hydrogen carbonate, and the mixture was extracted with chloroform. The resulting organic layer was dried over anhydrous sodium sulfate, then the insolubles were filtered, and the filtrate was concentrated under reduced pressure. The resulting residue was dissolved in 3 mL of chloroform, poured onto 3 mL of a tetrahydrofuran solution containing 257 mg of S-(−)-1-(4-bromophenyl)ethylamine and 224 μL of triethylamine, and the mixture was stirred overnight at room temperature. To the reaction mixture was added a saturated aqueous solution of sodium hydrogen carbonate, and the mixture was extracted with chloroform. The obtained organic layer was washed with saturated brine and dried over anhydrous sodium sulfate. The insolubles were filtered, the filtrate was concentrated under reduced pressure, and then the obtained residue was purified by silica gel column chromatography (eluent: chloroform/methanol=20/1), to obtain 252 mg of 2-{[(1S)-1-(4-bromophenyl)ethyl]amino})-4-(8-methylimidazo[1,2-a]pyridin-3-yl)pyrimidine-5-carbonitrile [3-1] (hereinafter, referred to as the compound [3-1]) as a pale yellow oily product.