36082-50-5

Colourless Oil

Starting material for the synthesis of trisubstituted pyrimidines via a combination of nucleophilic substitution and palladium-catalyzed aryl cross-coupling.1

General procedure for the synthesis of 5-bromo-2,4-dichloropyrimidine from 5-bromouracil: 5-bromouracil (6.0 g, 31.4 mmol) was placed in a reaction flask with phosphorus pentachloride (PCl5, 16.4 g, 87.9 mmol) and 1,1,2-trichloroethane (50 mL) was added as solvent. The reaction mixture was heated to reflux and the transformation of the mixture from suspension to a light yellow transparent solution was observed. The reaction progress was monitored by thin layer chromatography (TLC) and after confirming the complete conversion of the feedstock, the reaction mixture was cooled to room temperature. Subsequently, the reaction mixture was rapidly poured into stirred ice water and stirring was continued for 1 hour. The aqueous phase was extracted with dichloromethane (DCM, 3 x 50 mL), the organic layers were combined and dried with anhydrous magnesium sulfate (MgSO4). The solvent was removed by evaporation under reduced pressure to give a light yellow transparent liquid crude product. Finally, the crude product was purified by silica gel column chromatography to obtain the target compound 5-bromo-2,4-dichloropyrimidine as a colorless transparent liquid (99.5% yield, 97% purity).

[1] Patent: CN108117523, 2018, A. Location in patent: Paragraph 0039; 0041; 0043; 0044; 0045
[2] Purinergic Signalling, 2017, vol. 13, # 1, p. 89 - 103
[3] Patent: CN105237483, 2016, A. Location in patent: Paragraph 0039; 0040; 0041; 0042; 0043
[4] Patent: US4299961, 1981, A
[5] Journal of the American Chemical Society, 1934, vol. 56, p. 134,138