To a suspension of 8-chloroquinazoline-2,4(1H,3H)-dione (5.1 g, 25.9 mmol) in toluene (50 mL) and hexamethyldisilazane (HMDS, 10.4 g, 64.9 mmol) was added sulfuric acid (0.25 g, 2.6 mmol). The mixture was heated to reflux and refluxed for 8 h until a clear solution was obtained. The solvent and excessive HMDS was removed via vacuum evaporation, and methyl 3-(bromomethyl)benzoate (5.9 g, 25.9 mmol) and DMF (1 mL) was added to the residue. The reaction mixture was heated to 160° C. and was stirred at this temperature for 3 h. It was diluted with 1,4-dioxane (6 mL) at 100° C., and then methanol (10 mL) was added at 70° C. and it was stirred for 30 min. The mixture was cooled to 5° C. and the precipitates were collected. The solids was washed with methanol (10 mL) and water (20 mL), dried under vacuum for 12 h to give the title compound 8-chloro-3-(3-methoxycarbonylbenzyl)quinazoline-2,4(1H,3H)-dione (2.6 g, 29.1% yield) as gray solid. MS: m/z 477.1 [M+H]+. The filtrate was concentrated, and the residue was purified by preparative TLC (PE:EA=1:1) to give the other title compound 8-chloro-1-(3-methoxycarbonylbenzyl)quinazoline-2,4(1H,3H)-dione (0.2 g, 1.8%) as yellow solid. MS: m/z 477.1 [M+H]+.
