Sulfated zirconia and phosphotungstic acid catalyzed synthesis of some biologically potent heterocyclic compounds

Abstract

Sulfated zirconia and phosphotungstic acid (PWA) have been used as catalysts for the synthesis of some biologically potent 3,4-dihydropyrimidin-2(1H)-ones and aryl-14Hdibenzo[ a.j]xanthenes under solvent free conditions. Both the solid acid catalysts are found to be active for the synthesized compounds under mild reaction conditions. The 3,4-dihydropyrimidin-2(1H)-ones were synthesized in a single step using multicomponent condensation of aryl aldehyde, urea derivatives and β-dicarbonyl compounds using PWA or sulfated zirconia as catalysts. The generality of this protocol has been demonstrated by synthesizing a variety of functional dihydropyrimidin-2(1H)-ones in excellent yield and short reaction time. Phosphotungstic acid has also been demonstrated as an efficient catalyst for the condensation of aryl aldehydes and β-napthol to produce aryl-14H-dibenzo[a.j]xanthenes under solvent-free conditions. The reaction is found to proceed quickly in presence of catalytic amount of phosphotungstic acid and brief exposure to microwave to afford the products in good yield.