Tungstophosphoric acid/mesoporous silicas as suitable catalysts in quinoxaline synthesis

Abstract

Quinoxalines and their derivatives are of great value in the chemical and biological sciences. These compounds are found in dyes, agrochemicals, and are used as building blocks of drugs for the treatment of different diseases. Quinoxalines and their derivatives are synthesized by a heterogeneous catalysis procedure that involves the condensation of 1,2-dicarbonyl compounds with aromatic 1,2-diamines in an aprotic organic solvent at low temperature, in the presence of an acid catalyst composed of tungstophosphoric acid immobilized on mesoporous silica nanoparticles. The reaction process is very simple and the catalyst, besides being very active and selective, can be easily isolated from the reaction medium and reused in subsequent reactions without considerable loss of activity. Quinoxalines are obtained in short reaction time with excellent yields and high purity.