AcMIM]FeCl4: A Magnetically Separable Organocatalyst for the Clean Synthesis of Tetrahydrobenzo[b]pyran Derivatives

Abstract

Background: Recently, organic synthesis using ionic liquids (ILs) via green approach has attracted considerable attention to address the problem associated with environmental pollution. Magnetization of ILs provides added advantages of separation by external magnet. This can be accomplished by incorporation of high-spin iron(III) in the form of tetrachloro or tetrabromoferrate( III). Thus, synthesis of novel magnetically separable ILs for organic transformations is highly desirable. Results: [AcMIm]FeCl4 ionic liquid showed excellent catalytic activity in the one pot threecomponent synthesis tetrahydrobenzo[b]pyran derivatives at room temperature in excellent yields (94-98 %) within short reaction time (15-20 min.). The ILs were recovered and reused for at least six times with the minimum loss of catalytic activity. Methods: Here, we have demonstrated the excellent catalytic activity of acid functionalized magnetic Ils, [AcMIm]FeCl4 in one-pot multicomponent reactions for the synthesis of biologically important tetrahydrobenzo[b]pyran derivatives. Conclusion: A facile and convenient methodology has been developed for the synthesis of bio-active tetrahydrobenzo[b]pyran derivatives using [AcMIm]FeCl4 ionic liquid as an sufficient and reusable catalyst under environment-benign conditions.