Solventless Synthesis of Quinoline Derivatives: Acceleration of Friedländer Reaction by Supported Heteropoly Acids

Abstract

Different Keggin type heteropoly acids (HPAs) and supported ones on solids with different nature and textural properties were used in the Friedländer reaction in order to obtain quinoline derivatives. This conversion has been preceded by tungstophosphoric acid supported on silica, KSF and activated carbon as optimized catalysts in high yields and short reaction times. The general applicability of this method is demonstrated by using various substrates including ketones, β-ketoesters and β-diketones. For most substrates the reaction worked well. These catalysts were found to be reusable and considerable catalytic activity could still be achieved after the fourth run.

Keywords: Friedländer reaction, quinoline derivatives, heteropoly compound, supported catalysts, solvent-free condition