The general procedure for the synthesis of 4,6-dichloro-2-(methylsulfonyl)pyrimidines from 4,6-dichloro-2-methylthioalkylpyrimidines is as follows:
Example 27: Synthesis of 4,6-dichloro-2-(methylsulfonyl)pyrimidine
Commercially available 4,6-dichloro-2-methylsulfanylpyrimidine (Aldrich, 21.0 g, 107.0 mmol, 1 eq.) was dissolved in dichloromethane and cooled in an ice bath. Subsequently, 3-chloroperoxybenzoic acid (60.0 g, 77% wt, 268.0 mmol, 2.5 eq.) was added in batches. The resulting white suspension was stirred at room temperature for 4 hours. Upon completion of the reaction, it was washed sequentially with a mixture of 1 M sodium thiosulfate solution and saturated sodium bicarbonate solution (1:1, v/v, 200 mL x 3), saturated sodium bicarbonate solution (100 mL x 3) and brine (100 mL x 1). The organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The product was dried under high vacuum overnight to give the title compound EPO27 as a white solid (22.0 g, 91% yield). Thin layer chromatography Rf value was 0.20 (unfolding agent: 20% ethyl acetate/hexane); mass spectrum m/z 227 (calculated value 227, corresponding to molecular formula C5H4Cl2N2O2S+).
