1, 1′-Sulfinyldiethylammonium Bis (Hydrogen Sulfate) as a Recyclable Dicationic Ionic Liquid Catalyst for the Efficient Solvent-free Synthesis of 3, 4-Dihydropyrimidin-2(1H)-ones via Biginelli Reaction

Objective: A facile and efficient method for synthesis of 3, 4-dihydropyrimidin-2(1H)-ones via Biginelli reaction catalyzed by a novel dicationic Bronsted acidic ionic liquid, [(EtNH2)(2)SO][HSO4](2), has been successfully developed. Materials and Methods: 3, 4-Dihydropyrimidin-2(H-1)-ones were synthesized through one-pot condensation of aromatic aldehydes, ethyl acetoacetate, and urea under solvent-free conditions using ARTICLE HISTORY [(EtNH2)(2)SO][HSO4](2) as a novel catalyst. The progress of the reaction was monitored by thin-layer chromatography (ethyl acetate / n-hexane = 1 / 5). The products have been characterized by IR, H-1 NMR, C-13 NMR, and also by their melting points. Results: In this research, a library of dihydropyrimidinone derivatives was synthesized via Biginelli reaction under solvent-free conditions at 120 degrees C using [(EtNH2)(2)SO][HSO4](2) as a catalyst. Various aromatic aldehydes, as well as heteroaromatic aldehydes, were employed, affording good to high yields of the corresponding products and illustrating the substrate generality of the present method. In addition, the prepared dicationic BrOnsted acidic ionic liquid can be easily recovered and reused. Conclusion: 1, P-Sulfinyldiethylammonium bis (hydrogen sulfate), as a novel dicationic ionic liquid, can act as a highly efficient catalyst for the synthesis of 3, 4-dihydropyrimidin-2(H-1)-ones under solvent-free conditions.