Synthesis of 3,4-dihydropyrimidin-2(1H)-ones via Biginelli reaction using nano(BF3/Al2O3/SiO2) as a green catalyst under solvent-free condition

Multi-component reactions (MCRs) such as biginelli reaction are powerful strategies for the one-pot synthesis of organic compounds such as dihydropyrimidinone derivatives (DHPMs). The first biginelli-like reaction was reported by Wang [1]. Biginelli reaction involves the cyclocondensation of an aldehyde, a β-ketoester and urea or thiourea. biginelli products have potential in pharmaceutical applications such as anti-viral, anti-tumor, anti-bacterial, anti-inflammatory, anti-hypertensive and alpha antagonists [2].Solid acid nano catalysts which are bridges between homogeneous and heterogeneous catalysts, exhibit higher activity and selectivity than their corresponding bulk materials [3]. Heterogeneous catalysts have been applied in organic reactions in recent years. nano kaolin supported boron trifluoride is a catalyst which is reusable, cheep, readily, available, eco-friendly, versatile and efficient for promotion of many acid catalyzed organic reactions without the use of harmful solvents. In this study, we report our results for the synthesis of 3,4-dihydropyrimidinones (DHPMs) or their analogous thioketones by a one-pot cyclocondensation of acetoacetates, aryl aldehydes and urea or thiourea using nano kaolin supported boron trifluoride (BF3/Al2O3/SiO2) as catalyst under solvent-free conditions (Scheme1)