A novel and facile synthesis of 2-oxo-1,2-dihydropyridine-fused 1,3-diazaheterocycles via heterocyclic ketene aminals and Konevenagel adducts formed by phthalic anhydride and ethyl cyanacetate

Abstract An efficient synthetic pathway to 2-oxo-1,2-dihydropyridine-fused 1,3-diaza heterocycles from heterocyclic ketene aminals, phathalic anhydride and ethyl cyanacetate was established. This protocol involved aza-ene reaction/imine-enamine tautomerization/enamine-ester exchange/ring-opening reaction sequence.