SYNTHESIS OF THIENO[2,3-C]PYRIDINES AND RELATED HETEROCYCLIC-SYSTEMS

1-Isopropyl-4-piperidone (1) reacts with sulphur and active methylene nitriles to give thienopyridines (2a-c). Compounds 2a, b react with CS 2 in pyridine to produce pyridothienopyrimidines (3a, b) which upon me thylation with Mel give S-methylated derivatives (4a, b). Dibenzyliden e compound (5) reacts with hydrazine hydrate, phenyl hydrazine, thiour ea malononitrile or cyanoacetamide to give compounds 6-9 respectively. Piperidylidene malononitrile (10) reacts with benzaldehyde to give de rivative 11 which undergoes an addition reaction with malononitrile to give 12 which is also obtained by reacting 1 with one mole of benzald ehyde and two moles of malononitrile.