Preparation Of Magnetic Nanospheres Supported Bulky N-heterocyclic Carbene Palladium Catalyst And Its Application In The Suzuki Coupling Reaction

Suzuki-Miyaura coupling reaction, as a key approach of biaryls synthesis, was afoci in organic synthesis since it has been discovered. For decades, phosphine alwaysbeen used as a ligands for Palladium catalysts in Suzuki reactions, which is high toxic,low stability and also hard to separate as well as recovery. In this work, a magneticnanoparticles were used as a supporter for NHCs (N-heterocyclic carbine) palladiumcatalyst. It exhibited a high activity (TON was reached114000) and excellentrecoverability that the activity with no decay after21runs.These were mainly contains in this paper:A composite nanoparticles were polymerized by VBC-DVB-Fe3O4throughminiemulsion polymerization. It has a prefect magnetic responsibility and easy todisperse by ultrasonic, and the diameter was between100-150nm.Two different imidazolines was prepared and then immobilized on thenano-supporter directly, then five kinds of catalysts were obtained through differentways.The experiments show that the catalysts have very good activity and stability,even in reactions between inertness aryl chlorides and phenylboronic acid.It probably have two pathways in catalytic cycle of Suzuki reaction that usedNHCs palladium catalysts. The bulky steric effect may also worked in oxidativeaddition, and auxiliary ligands have a significant impact on catalysts.