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

摘要

New versatile enaminonitrile-type building blocks,3-aminothieno[2,3-b]pyridine-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.