Synthesis of 4-(2,4-dioxo-5-pyrimidyl)-1,4-dihydropyridine derivatives

Hantzsch synthesis of 5-formyluracil (1), methyl acetoacetate (2) and methyl 3-aminocrotonate (3) gave 2,6-dimethyl-4-(2,4-dioxo-5-pyrimidyl)-1, 4-dihydropyridine-3, 5-dicarboxylic acid dimethylester (4a) in 54.6% yield. As the same procedure, 1,3-dimethyl-5-formyl-uracil (6) gave 2,6-dimethyl-4-(1,3-dimethyl-2,4-dioxo-5-pyrimidyl)-1, 4-dihydropyridine-3,5-dicarboxylic acid dimethyl ester (7a) in 52.2% yield.4a was methylated to afford7a also in 52% yield.