5-methyl-7-neopentyl-2H-pyrazolo[3,4-d]pyrimidine-4,6(5H,7H)-dione (236 mg, 1.0 mmol), 4-(4-(chloromethyl)phenyl)pyridine (305 mg, 1.5 mmol) and potassium carbonate (414 mg, 3.0 mmol) are suspensed in 3 mL of DMF. The reaction mixture is stirred at room temperature overnight, and then diluted with 100 mL of water. The mixture is extracted with methylene chloride four times (40 mL×4). The combined organic phase is dried over anhydrous sodium sulfate. After filtration, the filtrate is evaporated to dryness to give 510 mg of crude product, which is used in the next step without further purification. MS (ESI) m/z 404.2 [M+H]+.
