Reaction of N-benzylideneanilines with methyl 3-aminocrotonate catalyzed by inorganic solids

N-benzylideneanilines 1 react with methyl 3-aminocrotonate 2 in the presence of solid acidic catalysts (K10 montmorillonite or ZF520 zeolite) to give dimethyl 4-(substituted)phenyl-2,6dimethyl-1,4-dihydropyridine-3,5-dicarboxylates 3 as major products. Methyl 2-(methoxycarbonylmethylene)-6-methyl-4-(substituted)phenyl-1,2,3,4-tetr ahydro-5-pyridinecarboxylates 4 and methyl 4-(methoxycarbonylmethyl)-2-methyl-6- (substituted)phenyl-3-pyridinecarboxylates 5 were isolated as minor products.