Studies on heterocyclic β-enaminonitriles: Synthesis of new condensed thieno[2,3-b]pyridines containing N-heterocyclic moieties

Abstract

New versatile enaminonitrile-type building blocks, 3-aminothieno[2,3-b]pyridine-2-carbonitriles 3a,b, were synthesized from 3-cyanopyridine-2-(1H)-thiones 1a,b. Interaction of 3a,b with triethyl orthoformate furnished the corresponding ethoxymethylideneamino derivatives 6a,b. Derivatives of heterocyclic systems having the pyrazole, pyrimidine, and pyridine rings were obtained from the key precursors 3a,b and 6a, respectively.

Keywords:

• Enaminonitriles
• Thienopyridines
• Pyridothienopyrimidines
• 1,2,4-Triazoles
• Hydrazinolysis
• Michael adducts

Acknowledgements

The authors wish to thank Professor Ayman W. Erian, a Research Fellow at McMaster University, Department of Chemistry, 1280 Main Street West, Hamilton, Ontario, Canada, L8S 4M1, for facilities provided during the progress of this research.