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.