Synthesis of Substituted 1,2-Dihydropyridines by the Reaction of (Ethoxymethylidene)cyanoacetic Ester and Arylamides of Acetoacetic Acid

The reaction of (ethoxymethylidene)cyanoacetic ester with arylamides of acetoacetic acid proceeds under heating in the presence of triethylamine or at room temperature in the presence of sodium ethoxide. According to the NMR and IR data, the intermediate adduct undergoes no other transformations but azacyclization which predominantly involves the cyano group and forms ethyl 5-acetyl-1-aryl-6-hydroxy-2-imino-1,2-dihydropyridine-3-carboxylates in yields of 30-78%. In some cases, 5-acetyl-1-aryl-2-hydroxy-6-oxo-1,6-dihydropyridine-3-carbonitriles resulting from cyclization involving the ethoxycarbonyl group were isolated as minor products (3-12%).