Synthesis of heterocyclic compounds using cyanoacetic acid hydrazide synthesis of pyrazolo[3,4-b]pyridine and pyrano[3,4-d]pyridazine derivatives

The reaction of cyanoacetic acid hydrazide with ethyl benzoylpyruvate and 3-arylhydrazono-2,4-dioxo-4- phenylbutanoates occurs with formation of pyrazolo[3,4-b]pyridine-4-carboxylate (3) and pyrano[3,4-d]pyridazine-1,4-diones (8a-c), respectively. The compound 3 reacts with hydrazine hydrate and phenyl isocyanate to afford pyrazolo[3,4-b]pyridine derivatives 4 and 5, respectively. The chemical structure of the compounds has confirmed by analytical, IR, 1H NMR and 13C NMR spectral data.