Efficient Synthesis of Benzo[b]pyrans and Knoevenagel Products Using Magnetically Separable Nano TPPA-IL-Fe3O4

A simple, efficient, and green practical approach to Knoevenagel condensation of malononitrile and different aldehydes has been developed using an ionic liquid functionalized on Fe3O4 magnetic nanoparticles as heterogeneous catalyst. This nanostructural catalyst has also been applied for the synthesis of 4H-benzo[b]pyran derivatives in water at room temperature in short reaction time. All of the products were obtained in good to excellent yields. The TPPA-IL-Fe3O4 catalyst was used at least seven times with comparable activities to the fresh catalyst.