Step A: Preparation of 5-bromopyrimidin-4(3H)-one: bromine (16.0 mL, 312 mmol) was slowly added dropwise to a suspension of chloroform (1 L) of 4-hydroxypyrimidine (30 g, 312 mmol) at 0 °C. Methanol (10 mL) was then added as a catalyst and the reaction mixture was stirred at 0 °C for 12 hours. Upon completion of the reaction, the resulting white solid product was collected by filtration, washed sequentially with hexane and ether, and then dried under vacuum to afford 5-bromopyrimidin-4-one (50 g, 91.5% yield). The structure of the product was confirmed by 1H NMR (400 MHz, DMSO-d6): δ 11.15 (broad single peak, 1H), 8.42 (single peak, 1H), 8.40 (single peak, 1H).
