6-bromo-8-ethyl-2-(methylthio)pyrido[2,3-d]pyrimidin-7(8H)-one (150 mg, 0.50 mmol), phenylboronic acid (183 mg, 1.50 mmol), K3PO4 (318 mg, 1.50 mmol) and Pd(PPh3)4 (29 mg, 0.02 mmol) were mixed as solids and placed under argon. Argon was bubbled through the mixture of dimethoxyethane:ethanol:water (1:1:1, 2.0 mL) for 20 min. The solvent was added to the solid and the suspension was heated under microwave irradiation at 120° C. for 1 h. After completion, the reaction mixture evaporated to dryness, the crude product was purified by silica gel column chromatography using dichloromethane:ethyl acetate (100:0.5) to yield 8-ethyl-2-(methylthio)-6-phenylpyrido[2,3-d]pyrimidin-7(8H)-one as an off-white solid (121 mg, 0.41 mmol, 81%). ESMS m/z 298 (M+H)+; 1H NMR (400 MHz, CDCl3) δ ppm 8.59 (s, 1H), 8.03 (s, 1H), 4.55 (q, J=7.2 Hz, 2H), 2.63 (s, 3H), 1.35 (t, J=7.2 Hz, 3H).
