Utility of 5-antipyrylazopyridin-2-thione: Synthesis of 5-antipyrylazothieno {[}2,3-b] pyridines and 4-antipyrylazopyrido {[}3,4-d] pyridazine derivatives

5-Antipyrylazopyridin-2-thione 1 reacted in sodium ethoxide with a-halo compounds such as phenacyl bromide, ethyl alpha -chloroacetoacetate, chloroacetone, chloroacetic acid to give the corresponding alkylmercaptopyridines (2,4,6 and 8) and thieno {[}3,4-d] pyridine derivatives (3,5 \& 9) respectively. On the other hand, alkylmercaptopyridine (2,4,6 and 8) could be converted to the corresponding thieno {[}3,4-d] pyridines (3,5-and 9). Also, compound 1 reacted with p-diketones such as acetylacetone and benzoylacetone to afford acyclic products 10 and 11 respectively. This contrasts the reaction of compound 1 with cyclohexanone to yield 6,7-tetramethylene isoquinoline derivative 12. Compound 1 also reacted with cyanogen bromide to give compound 7. Compound 1 could be coupled with diazonium salts such as p-chlorobenzenediazonium chloride 13 and others to afford the corresponding pyrido {[}3,4-d] pyridazine derivatives (18, 19, 20, 21 and 22) respectively. The structure of all products were established and confirmed on the basis of the elemental analysis and spectral data.