The general procedure for the synthesis of 8-bromoquinazoline-2,4(1H)-dione from 2-amino-3-bromobenzoic acid (10.8 g, 50 mmol, 1 eq.) and urea (15 g, 250 mmol, 5 eq.) was carried out as follows: a mixture of the above two raw materials was stirred and reacted for 3 hr at 200 °C. After completion of the reaction, the mixture was cooled to room temperature and slowly poured into ice water. The resulting solid product was collected by filtration and subsequently washed three times with deionized water to remove impurities. Finally, the product was dried under vacuum to afford 8-bromoquinazoline-2,4(1H)-dione as a yellow solid (12.1 g, about 100% yield).
