Studies on heterocyclic β-enaminonitriles: Synthesis of new condensed thieno2,3-bpyridines containing N-heterocyclic moieties

摘要

New versatile enaminonitrile-type building blocks, 3-aminothieno2,3-fcpyridine-2-carbonitriles 3a,b, were synthesized from 3-cyanopyridine-2-(1H)-thiones la,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.