8-bromo-3-methyl-3,7-dihydro-1H-purine-2,6-dione (2.450 g, 10 mmol),1-bromo-2-butyne (1.596 g, 12 mmol), Sodium carbonate (1.590 g, 15 mmol), and 20mL of acetone was added to a 100mL flask. The reaction system was heated to 40 ° C, and the reaction was stirred for 4h. After the reaction was cooled to room temperature, suction filtration was performed, and the filter cake was washed with methanol to obtain a crude product as a pale yellow solid. The crude product was reconstituted with dichloromethane and cyclohexane. Yield 2.912 g of 8-bromo-7-(but-2-ynyl)-3-methyl-1H-purine-2,6(3H,7H)-dione. The yield was 98%, and the purity was 99.9%.
