Reactions with cyanothioacetamide derivative: Synthesis and reactions of some thieno[2,3-b]pyridine, pyridothienopyridazine, pyrazolo[3,4-b]pyridine and pyridopyrazolo-1,2,4-triazine derivatives

Thiocarboxamidocinnamonitrile derivatives 3a,b reacted with ethyl-benzoylacetate (4) to give pyridinethione derivatives 5a,b which were used as starting materials for synthesis of several heterocyclic compounds. Reactions with phenacyl bromides 6a,b, chloroacetone (8), alpha-chloroacetylacetone and methyl iodide gave thieno[2,3-b]pyridines 7a-d; 2-S-methylacetylpyridine derivatives 9a,b; 2-S-methyldiacetyl pyridine derivatives 11a,b and 2-S-methyl pyridine derivatives 14a,b respectively. Several cyclization reactions were performed with 10% KOH, nitrous acid and hydrazine hydrate to give an additional ring on 9a,b, 10a,b, 11a,b and 14a,b.