Alkylation and reductive dethionation of 2-thioxo- and 1,2,3,4-tetrahydropyrimidine-5-carboxylic acid derivatives

2-Methylthio-1,4-dihydropyrimidines were obtained by methylation of 2-thioxo-4-phenyl-5-methoxycarbonyl-6-methyl-1,2,3,4-tetrahydropyrimidine or its 1-methyl derivative in a neutral medium. The alkylation of tetrahydropyrimidine-2-thiones in the anionic form leads to S- and S,N-methylation products. Iodoacetamide alkylates pyrimidine-2-thione with the formation of thiazolidino[3,2-a]pyrimidine derivatives. The reductive dethionation of derivatives of tetrahydropyrimidine-2-thiones and 2-methylthio derivatives of 1,4- and 3,4-dihydropyrimidines was accomplished.