49844-90-8

97229-11-3

General procedure for the synthesis of 4-chloro-2-(methylsulfonyl)pyrimidine from 2-methylthio-4-chloropyrimidine: 2-methylthio-4-chloropyrimidine (7.25 mL, 62.3 mmol) and 95% ethanol (100 mL) were added to a 250-mL single-necked flask, and the mixture was cooled to 0 °C under magnetic stirring. 30% hydrogen peroxide (14.4 mL, 187 mmol) and ammonium molybdate tetrahydrate (2.18 g, 1.87 mmol) were slowly added dropwise. After the dropwise addition, the reaction mixture was gradually warmed up to room temperature and stirred overnight under nitrogen protection. Upon completion of the reaction, the solvent was removed by distillation under reduced pressure, followed by evaporation with the addition of water (200 mL). The resulting product was dried with anhydrous sodium sulfate, filtered and concentrated, and finally purified by silica gel column chromatography to give 10.2 g of white solid product in 85.7% yield.