Synthesis
The general procedure for the synthesis of 2,4-dibromopyrimidine from pyrimidine-2,4(1H,3H)-dione was as follows: phosphorus bromide (40.13 g, 0.14 mol) was mixed with uracil (3 g, 0.027 mol) and the reaction was stirred for 2 hr at 125 °C. After completion of the reaction, it was cooled to room temperature and the reaction mixture was slowly poured into 500 g of ice water and neutralized with solid sodium bicarbonate. Subsequently, the aqueous phase was extracted twice with 150 ml of dichloromethane. The organic phases were combined, dried and concentrated under reduced pressure to give 6.2 g of crude product. Finally, the crude product was purified by fast silica gel column chromatography to give 5 g of white solid product in 78.5% yield.
References
[1] Patent: CN106632077, 2017, A. Location in patent: Paragraph 0017; 0018; 0019; 0025; 0026; 0027; 0032-0034
[2] Journal of Heterocyclic Chemistry, 2005, vol. 42, # 4, p. 509 - 513
[3] Journal of Heterocyclic Chemistry, 1995, vol. 32, # 4, p. 1159 - 1163
