The Core‐Shell Magnetic Mesoporous Microspheres Immobilized NHC‐Palladacycles: An Efficient and Recyclable Catalyst for Suzuki‐Miyaura Cross‐Coupling of Pharmaceutical Synthesis

Abstract

AbstractThe core‐shell magnetic mesoporous microspheres immobilized NHC‐palladacycles (NHC=N‐heterocyclic carbene) catalyst with constrained aliphatic linker group (Fe3O4@mSiO2@NHC−Pd) were readily prepared by the well‐designed method, which showed higher palladium loading (0.20 mmol g−1) and higher catalytic activity than the non‐mesoporous catalysts (Fe3O4@SiO2@NHC−Pd) prepared by the same process in the Suzuki‐Miyaura cross‐coupling reactions of aryl chlorides and aryl boronic acids. Herein, Fe3O4@mSiO2@NHC−Pd could be used 12 times without significant activity loss, and no palladium leakage was detected in both the product and catalytic residue, highlighting the efficiency of our strategy for immobilizing the catalyst. Remarkably, this approach allows the synthesis of important drug intermediates 2‐aryl‐4‐aminoquinazolines and o‐tolylbenzonitrile (OTBN).