Catalytic activity of tungstophosphoric acid supported on carriers of diverse acidity in the synthesis of enaminones

Tungstophosphoric acid (PW), supported on different metal oxide (TiO(2), gamma-Al(2)O(3), K 10 and KSF) and activated carbon were used in the condensation of aniline with ethylacetoacetate to afford the corresponding beta-enaminone. Catalytic activity was discussed in relation with the acid strength of catalysts. The best catalytic activity was obtained with PW/TiO(2). Effect of PW loading, solvent and catalyst reusability was studied to introduce the best reaction conditions. Based on the above experimental findings, various beta-enaminones were synthesized in excellent yield within a few minutes under solvent free condition. (C) 2008 Elsevier B.V. All rights reserved.