[Synthesis]
Synthesis of N-(5-aminopyridin-2-yl)-4-(trifluoromethyl)benzamide: Compound C' (500 mg, 1.6 mmol) was dissolved in ethyl acetate (4 mL) and palladium carbon (catalytic amount) was added. The mixture was stirred overnight at room temperature in a hydrogen balloon atmosphere. The progress of the reaction was monitored by thin layer chromatography (TLC, unfolding agent: ethyl acetate/hexane = 1:2). After completion of the reaction, the mixture was filtered through diatomaceous earth and the filtrate was concentrated by decompression to give the crude product (413 mg, 1.5 mmol). The crude product was recrystallized from a solvent mixture of ethyl acetate/hexane to give N-(5-aminopyridin-2-yl)-4-(trifluoromethyl)benzamide 1 (white plate-like crystals, 314 mg, 70% yield). The melting point of the product was 140.5-141.5 °C. 1H NMR (300 MHz, DMSO-d6) δ: 10.62 (s, 1H, NH), 8.16 (d, 2H, J = 8.0 Hz, Ar-H), 7.84 (d, 2H, J = 9.0 Hz, Ar-H), 7.75 (dd, 2H, J = 3.0, 1.0 Hz, Ar- H), 7.03 (dd, 1H, J = 9.0, 3.0 Hz, Ar-H), 5.22 (s, 2H, NH2). |