Bismuth(III) Triflate, Bi(OTf)3: Green and Reusable Catalyst for One-Pot Synthesis of Fused Nitrogen/Oxygen Heterocycle Derivatives

There is an increasing demand for the development of catalytic reagents that are nontoxic due to the growing environmental concerns in the present organic transformation. Bismuth(III) compounds have significant potential as catalysts for a range of organic synthesis due to their low toxicity, strong Lewis acid catalytic activity, and great flexibility. In this research work, a series of various chemically and pharmacologically important six-membered fused nitrogen-/oxygen-based heterocycle derivatives were efficiently prepared via a one-pot multicomponent reaction starting from aromatic aldehydes, malononitrile, and barbituric acid in presence of green and reusable Lewis catalyst bismuth(III) triflate, that is, Bi(OTf)(3) in EtOH/H2O (1:1) media. Bi(OTf)(3) has the additional benefit of being reusable catalyst, ready availability, eco-friendliness, and easy to handle to obtain corresponding products in excellent yields (83%-94%). Structure of all synthesized products was characterized on the basis of FT-IR, H-1-NMR, C-13-NMR, and ESI-MS analysis.