A new and practical method for the synthesis of 6-aryl-5,6-dihydropyrido[2, 3-d]pyrimidine-4,7(3H,8H)-diones

A one step general synthetic methodology for the synthesis of 6-aryl-5,6-dihydropyrido[2,3-d]pyrimidine-4,7(3H,8H)-diones (17{x} (G = NH ₂) and 20{x } (G = SMe) is described. This methodology is based on reacting a 2-aryl-substituted acrylate (16{x}) with the corresponding 6-aminopyrimidin-4(3H) -one (13 (G=NH₂)); 19 (G =SMe)) in presence of a base under microwave irradiation. The resulting pyrido[2,3-d ]pyrimidines present an aryl substituent at position C6, precisely the one directly related to the biological activity of such heterocycles. These protocols have been extended to other 2-alkyl-substituted and 3-alkyl (or aryl)-substituted acrylates but with lower yields.