A revision for the synthesis of β-enaminones in solvent free conditions: efficacy of different supported heteropoly acids as active and reusable catalysts.

Catalytic performance of different supported heteropoly acids (HPAs) in the synthesis of β-enaminones and β-enamino esters from various substituted amines and β-diketones or β-keto esters has been studied. In order to improve the yield and reaction time, the effect of various solvents, HPA loading, different amount of the catalyst and solventless conditions have been investigated. 40% (w/w) PW/SiO2 was found to be a very efficient and reusable catalyst in comparison with others, under solvent free conditions. In this eco-friendly approach, the usage of organic solvents and hazardous reagents were minimized. Also, a high yield of products within short reaction times were obtained. [ABSTRACT FROM AUTHOR]