One-pot synthesis of Biginelli and Hantzsch products catalyzed by non-toxic ionic liquid (BMImSac) and structural determination of two products

Abstract: In this paper, both 1,4-dihydropyridinones (Hantzsch products) and 3,4-dihydropyrimidinones (Biginelli products) are synthesized in one-pot of aldehydes, β-dicarbonyl compounds and urea, catalyzing by non-toxic room temperature ionic liquid 1-n-butyl-3-methylimidazolium saccharinate (BMImSac). The ionic liquid (BMImSac) is environmentally benign associated with ionic liquid with F−. In order to improve the yield and selectivity, the effects of the mole proportion of reactants and solvents are investigated. Interestingly, by increasing the amount of ethyl acetoacetate or utilizing water as solvent, an unexpected by-product, Hantzsch product which is distinct from Biginelli product, is generated. All Biginelli and Hantzsch products are simultaneously purified and characterized by IR, 1H NMR and 13C NMR, of which one Biginelli product (4h) and one Hantzsch product (5b) are structurally determinated by X-ray single crystal diffraction. The crystal data for 4h: triclinic system, P-1 space group, a =7.515(3)Å, b =9.011(4)Å, c =11.218(5)Å, α =106.288(6)°, β =104.644(6)°, γ =100.234(6)°, Z =2, V =679.7(5)Å3, D c =1.36g/cm3, R 1 =0.0603. The crystal data for 5b: monoclinic system, P2(1)/c space group, a =9.765(3)Å, b =7.391(2)Å, c =24.795(7)Å, β =93.669(5)°, Z =4, V =1785.7(9)Å3, D c =1.292g/cm3, R 1 =0.0440. [Copyright &y& Elsevier]