General procedure: 3-methyl-7-(2-butyn-1-yl)-8-bromoxanthine (Compound VII, 1.34 g, 4.5 mmol), potassium carbonate (1.42 g, 10.3 mmol), 2-chloromethyl-4-methylquinazoline (Compound III, 0.87 g, 4.5 mmol), tributylmethylammonium chloride (phase transfer catalyst, 0.53 g , 2 mmol) and 2-methyltetrahydrofuran (50 mL) were added sequentially to the reaction flask. The reaction mixture was heated to reflux and maintained for 3 to 5 hours. Upon completion of the reaction, it was cooled to room temperature and the reaction was quenched by the addition of water (100 mL). The reaction mixture was filtered, the filter cake was collected and dried at 45 °C to afford 1-[(4-methylquinazolin-2-yl)methyl]-3-methyl-7-(2-butyn-1-yl)-8-bromoxanthine (Compound VIII).
Yield: 1.78 g (87.1% yield).
Mass spectrum (MS): [M + H]+ = 453/455.
1H-NMR (400 MHz, DMSO-d6): δ 1.79 (t, J = 2.3 Hz, 3H), 2.89 (s, 3H), 3.44 (s, 3H), 5.11 (q, J = 2.2 Hz, 2H), 5.35 (s, 2H), 7.67 (m, 1H), 7.80 (d, J = 8.3 Hz, 1H), 7.75 ( m, 1H), 8.24 (d, J = 8.1 Hz, 1H).
