Ethyl Acetate → 3-(2-chloro-phenyl)-7-methylsulfonyl-3,4-dihydropyrimido[4,5-d]pyrimidin-2(1H)-one

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Reaction Steps

A suspension of 3-(2-chlorophenyl)-7-methylthio-3,4-dihydropyrimido[4,5-d]pyrimidin-2(1H)-one (4.1 g, 12.8 mmol) in 50 mL of chloroform was cooled in ice and treated with 70% 3-chloroperbenzoic acid (9.8 g, 39.8 mmol). The mixture was stirred at room temperature for 2 hours, then treated twice with 100 mL of 10% aqueous sodium thiosulfate and left to stir for 30 minutes. The reaction was diluted with 400 mL dichloromethane and the phases were separated. The organic phase was washed with a saturated aqueous solution of sodium bicarbonate and then dried over magnesium sulfate and filtered. Concentration of the filtrate under reduced pressure gave a solid which was stirred with ethyl acetate, then filtered to give 2.6 g of 3-(2-chloro-phenyl)-7-methylsulfonyl-3,4-dihydropyrimido[4,5-d]pyrimidin-2(1H)-one (sulfone 11.1) as a white solid. (MH+=364)

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