The Synthesis Of Imidazole-based Phosphine Ligands And Their Application In Suzuki Coupling Reaction

Since N-heterocyclic carbene was first discovered in1991, it has arousedwidespread concern.N-heterocyclic carbene has a strong σ electron giving ability anda weak л electron accepting capability,it can coordinate with many metals to formmetal complexes,it has many incomparable advantages when compared withtraditional organic phosphine ligands:when it is exposed to water and air, it is alsovery stable so that it is not easy to be oxidized;With a larger carbenic-metal bondenergy, which is not easy to be decomposed under the heating conditions.Based on theabove advantages, N-heterocyclic carbenes and their metal complexes,are widely usedin the field of organometallic chemistry, organic catalysis, medicine.The imidazolephosphine compounds as a class of N-heterocyclic carbene with a combination ofelemental phosphorus,it not only has the advantages of N-heterocyclic carbenes, alsodue to a combination with elemental phosphorus, result in improving its catalyticactivity significantly.Imidazole phosphine compounds have been developed rapidly inthe last decade,a large number of imidazole phosphonic compounds have beensynthesized,and they were widely used as ligands in cross coupling reactionsincluding Suzuki-Miyaura coupling, Heck reaction,Sonogashira reaction and thecatalytic effect is very good.Increasing the steric hindrance of the substituent groups appropriately and thenumber of N-heterocyclic carbene can significantly improve the stability ofN-heterocyclic carbenes, enhancing its catalytic activity, based on this we designedand synthesized nine imidazole phosphine compounds,The structures of thesecompounds were confirmed by IR,1H NMR,13C NMR,31P NMR.These imidazolephosphine compounds are used in the Suzuki coupling reaction.The Suzuki couplingreaction conditions are optimized,halogenated aromatic substrate were expandedunder the best Suzuki coupling reaction conditions.Finally,we have discussed the thecatalytic activity of imidazole phosphine compounds when they were used in Suzukicoupling reaction.