2-(Ethylthio)-7-iodoquinazolin-4(3H)-one (10.8 g, 32.5 mmol) was used as a raw material, which was dissolved in ethanol (40 mL), followed by the addition of 6N hydrochloric acid (40 mL). The reaction mixture was heated to reflux at 80 °C overnight, and upon completion of the reaction and cooling to room temperature, a large amount of white precipitate was observed to be generated. The precipitate was collected by filtration to afford the off-white solid product 7-iodoquinazoline-2,4(1H,3H)-dione (8.97 g, 96% yield). Mass spectrum (ESI) m/z 289.0.
