A convenient and facile synthesis of pyridine, pyridazine, pyrimido[4,5-c]pyridazine, pyrido[3,4-c]pyridazine, 1,6-naphthyridine and phthalazine derivatives

Ethyl 2-arylhydrazono-3-butyrates 2 reacted with 2-cyano-N-(4-methylphenyl) acetamide la and 2-cyano-N-(thiazol-2-yl)acetamide 1b to give the pyridinedione, 4 and pyridazine 5 derivatives in 3:1 ratio. The products 4 and 5 have been transformed into different phthalazine, pyrimido[4,5-c]pyridazine, pyrido[3,4-c]pyridazine and 1,6-naphthyridine derivatives. The chemical structures have been confirmed by analytical and spectral analysis.