Synthesis of Magnetic Nanoparticles and Polymer Supported Imidazolidinone Catalysts for Enantioselective Friedel‐Crafts Alkylation of Indoles

Abstract

AbstractThe copper catalyzed Huisgen cycloaddition has been used for the immobilization of enantiopure tbutyl‐imidazolidin‐4‐one on magnetic nanoparticles (MNP‐A, MNP‐B) at two different anchoring sites and a Merrifield resin support (PS). The obtained catalysts have been characterized by FTIR, elemental analysis, XRD and TEM. These catalysts have been used in alkylation of indoles with α,β‐unsaturated aldehydes affording the desired products in high yields with excellent enantioselectivities. MNP‐A with the magnetic nano‐functionalization at the amide nitrogen (N3) position shows relatively lower catalytic efficiency compared to MNP‐B with nanoparticles anchored at the O‐aryl residue. The PS, owing to its high loading of the catalyst, shows higher catalytic activity than MNP‐A and MNP‐B but the magnetic nanocatalysts show higher recycling efficiency than the PS as they can be easily separated from the reaction medium through simple magnetic decantation.