Efficient and easy Knoevenagel condensation of arylaldehydes with ethyl cyanocinnamate/thiazolidindione catalyzed by KF–Al2O3

Efficient and easy Knoevenagel condensation of a variety of arylaldehydes with active methylene-containing compounds such as ethyl cyanoacetate, thiazolidindione is reported, under three different conditions including (i) reflux in acetonitrile, (ii) reflux in acetic acid, and (iii) solvent-free conditions. In all conditions, the desired products are obtained in high yields after relatively short reaction times. Nevertheless, the reactions proceed faster, cleaner and in higher yields when they carry out in solvent-free fashion.