Polymer-Supported Dioxidovanadium(V) Complex-Based Heterogeneous Catalyst for Multicomponent Biginelli Reaction Producing Biologically Active 3,4-Dihydropyrimidin-2-(1<i>H</i>)-ones

Abstract

Dioxidovanadium(V) complex [VVO2(sal-aebmz)] (1) (where Hsal-aebmz = Schiff base derived from the condensation of salicylaldehyde and 2-aminoethylbenzimidazole) has been immobilized on chloromethylated polystyrene (PS-Cl) cross-linked with divinylbenzene to obtain [VVO2(sal-aebmz)]@PS (2), a heterogeneous complex. Both complexes, after characterization, have been used as catalysts to explore a single pot multicomponent (benzaldehyde or its derivatives, urea and ethyl acetoacetate) Biginelli reaction producing biologically active 3,4-dihydropyrimidin-2-(1H)-one (DHPM)-based biomolecules under solvent-free conditions in the presence of H2O2 as a green oxidant. Various reaction conditions such as amounts of catalyst and oxidant, temperature, time, and solvent have been optimized to obtain the maximum yield of DHPMs. The polymer-immobilized complex has been found to show excellent catalytic activity, giving ca. 95% yield of DHPMs under the optimized reaction conditions selectively. Oxidant plays an important role in enhancing the yield of DHPMs.

Keywords

• chloromethylated polystyrene
• dioxidomolybdenum(VI) complex
• multicomponent Biginelli reaction
• solventless conditions
• supported and unsupported catalysts