Magnetite L-proline as a reusable nano-biocatalyst for efficient synthesis of 4H-benzo[b]pyrans in water: a green protocol

LProline is known as the most favored organocatalystin enaminemediated reactions. Magnetic functionalization of this organocatalyst could solve its recovery and reuse problems. Herein we report the use of magnetic Lproline nanobiocatalyst for a simple and efficient onepot coupling reaction of dimedone,malononitrile, and aromatic aldehydes to afford the corresponding tetrahydrobenzo[b]pyrans as a significant class of heterocyclic compounds with great biological and pharmacological importance according to a green protocol. Low cost, facile handling, simple preparation, highstability, reusability,and low toxicityare some remarkable features ofthis nanobiocatalyst.