Pyridine catalyzed reaction of tetracyanoethylene and activated 1,3-dicarbonyl CH-acid compounds: A rapid and efficient synthesis of pyran annulated heterocyclic systems

A pyridine catalyzed reaction between tetracyanoethylene and various activated CH-acid compounds to afford the corresponding pyran annulated heterocyclic ring systems in high yield at room temperature within a few minutes, is described. The work-up procedure is very simple and the products do not require further purification.