A direct and efficient approach for the synthesis of new series of pyrido[3,4-c][1,5]benzothiazepine,
pyrido[4,3-d]triazolo[1',5'-a]pyrimidines, pyrido[4,3-d]tetrazolo [1',5'-a]pyrimidine and pyrido[4,3-4',5']pyrimido[1',2'-
a]benzimidazoles has been developed via condensation of o-aminothiophenol and heterocyclic amines each with 1-ethyl-
4-piperidinone and the appropriate aldehyde. The reactions were performed in refluxing acetonitrile in the presence of
molecular iodine as a catalyst. Also, the 1,3-dipolar cycloadditions of nitrilimines to the latter products were examined and were found to
be site- and regioselective. The structures of the new synthesized compounds were established on the basis of spectral data (Mass, IR, 1H
and 13C NMR) and elemental analyses.