TiO2 and TiO2 nanoparticles as efficient and recoverable catalysts for the synthesis of pyran annulated heterocyclic systems

Abstract

TiO2 catalyzed reactions between various activated CH-acids and tetracyanoethylene are described. This reaction affords the corresponding pyran annulated heterocyclic systems in high yields at room temperature in 3 h. The work-up procedure is very simple, and the products do not require further purification. The catalysts can be recycled and reused several times without observable loss of performance.