The Design And Synthesis Of A Novel Pincer Palladium Complexes And Their Application In Cross-coupling Reactions

In recent years,pincer pd complexes,which synthesized via concise strategies and showed stable properties and high activity and selectivity as catalysts in the cross-coupling reactions,have attracted more attentions.Several new pincer-types ofpd complexes were reported to date about the synthesis and catalytic activities.In this dissertation,it was described the synthesis of novel pincer palladium complexes and their applications to catalyze the Suzuki reaction and Heck coupling reaction.Part 1.Synthesis and Characterization of NCN-Pincer Palladium Complexes:Eight NCN-pincer palladium complexes were designed and prepared concisely.They were characterized by ¹HNMR,¹³CNMR,IR,element analysis and DSC-TGA.Amongst the complexes,three structures were confirmed by single X-ray diffraction.These results provided fundamental information for investigating the catalytic mechanisms as well as the relationships between the structures and the activities.Part 2.Catalytic Activity Test of NCN-Pincer Palladium Complexes in Suzuki Coupling Reaction and Heck Reaction:The prepared eight NCN-pincer palladium complexes were applied in Suzuki coupling reaction and Heck reaction.Results indicated that all the complexes showed good to excellent catalytic activity towards both Suzuki and Heck coupling reaction.When using phenylboronic acid as the model substrate in Suzuki coupling,catalyst 72 was quite effecient for almost all aryl bromides,no matter whether activated or nonactivated.And the activity was not sensitive toward air.A turnover number（TON） of 3.8×10⁴ was observed with the reaction of phenylboronic acid with 4-Bromoanisole even under aerobic conditions.Further more,72 was an effective catalyst for chloroarene substrates,for instance,for p-nitrochlorobenzene,yield of 89%was abtained with lmol%loading.As far as the Heck reaction was concerned,they were excellent catalysts to iodoarene substrates and good to bromoarene,yet unactive to chloroarene.TON up to 760000000 was observed for iodobenzene under the optimized condition.