The Application Of Phosphine Ligands Of Steric Hindrance And Bipyridine To Suzuki Coupling Catalyzed By Cyclopalladated Complexes Of Tertiary Amine

Based on the previous research work upon Suzuki coupling reaction catalyzed by cyclopalladated complexes developed by our group,this dissertation was mainly focused on improving the catalytic activity by the use of phosphine ligands with steric hindrance,and stabilizing the cyclopalladated complexes with bipyridine,maybe which could provide some useful information for developing effective and recyclable catalyst system upon C-C bond formation reaction.This dissertation consists of two parts:1.Suzuki coupling reaction catalyzed by tertiary benzylamine cyclopalladat ed complexes/phosphine ligands with steric hindranceTertiary benzylamine cyclopalladated complex is a kind of easy get,air and moisture stable catalyst.In this dissertation,a new catalytic system,using the tertiary benzylamine cyclopalladated complexes and phosphine ligands with steric hindrance as the catalyst,was developed and applied to the Suzuki coupling reaction.The results showed that using the special phosphine ligands could improve the catalyst's efficiency,and the yields increased with the increasing of the ligands' steric hindrance. In the model reaction of 4-Bromoacetophenone with boronic acid,the addition of ligand 26 could cut down ten times amount of the catalyst,cyclopalladated complexes, and the TON value was up to 1×10~6.Meanwhile,with DMA/dioxane(1:2,v/v)as the mixed solvent,not only the yield was improved but also the reaction temperature was lowered down from 165℃to 105℃.2.Study on the recyclable catalyst system for Suzuki coupling reaction:C yclopalladated complexes/bipyridineTo test the recycle of the up-mentioned catalytic system,2,2'-dipyridine was added to stabilize the cyclopalladated complexes,and inhibit the decomposing of cyclopalladated complexes into palladium black.In the model reaction of 4-Bromoacetophenone with boronic acid,the catalyst can be recycled 7 times with the yield＞90%.When with the inactive 4-chloroacetophenone as the substrate,after 4 times recycle,the yield was still 50%.Compared with the common supported method, the stabilization of cyclopalladated complexes with bipyridine has provided a convenient,feasible and easy way for developing recyclable catalytic system upon Suzuki coupling reaction.