Synthesis of pyrimidine derivatives by the reaction of ketene dithioacetals with amides

Abstract

AbstractReactions of methyl 2‐cyano‐3,3‐bis(methylthio)acrylate (1a) with carboxamides 2a‐g in the presence of sodium hydride in a mixture of benzene and N,N‐dimethylacetamide took place displacement with the methylthio group to give the corresponding methyl 3‐N‐acylamino‐2‐cyano‐3‐(methylthio)acrylates 3a‐g which were readily converted to the corresponding pyrimidine derivatives at reflux in methanol in good yields. Reactions of 2‐cyano‐3,3‐bis(methylthio)acrylonitrile (1b) with the carboxamides 2a‐f gave directly pyrimidine‐5‐carbonitrile derivatives 7a‐f. Ketene dithioacetals 1a,b smoothly reacted with thioamide 2g or urea 2h,i to give the expected pyrimidine derivatives 9,10a,b. Polyfunctionalized pyrimidines, thus obtained, were also used for the synthesis of fused pyrimidine derivatives.