Synthesis of 4-alkyl-substituted 1,2,3,4-tetrahydropyrimidin-2-ones by the Biginelli reaction

p-Toluenesulfinic acid is an effective catalyst for condensation of acetoacetic ester with urea and aliphatic or aromatic aldehydes, leading to formation of 4-substituted 6-methyl-5-ethoxycarbonyl-1,2,3,4-tetrahydropyrimidin-2-ones.M. V. Lomonosov State Academy of Fine Chemical Technology, Moscow 117571, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 979–982, July, 1998.