The Research On Synthesis And Catalysis Of N-heterocyclic Carbene-metal Complexes

Objective:A series novel N-heterocyclic carbene-metal complexes were designed and synthesized,and they have been successfully applied in catalytic reaction.The research on catalysis of several types reactions with high attention and wide application was carried out in this article.Moreover,synthesis of structural units with core framework of natural products and pharmaceuticals.Methods:The novel imidazolium ligands were synthesized through iodinated reaction,Suzuki-Miyaura coupling reaction,Heck reaction,aldimine condensation and cyclization reaction.Then the novel imidazolium ligands are coordinated with the transition metals such as copper,silver and palladium under the corresponding conditions to form novel N-heterocyclic carbene-metal complexes.The optimal reaction conditions were established by screening type and dosage of catalyst,solvent,base,temperature,time and other reaction conditions.Under the optimal reaction conditions,the catalytic activity of the N-heterocyclic carbene-metal complexes and relationship between different substrate were also investigated.Results:1.Six novel imidazolium ligands,four novel N-heterocyclic carbene copper complexes,three novel N-heterocyclic carbene silver complexes and two N-heterocyclic carbine palladium complexes were designed and synthesized.Their structures were characterized by ¹H NMR and ¹³C NMR,the single crystal structure was subjected to X-ray single crystal diffraction to obtain single crystal data.2.The N-heterocyclic carbene-metal complexes as catalyst acted an efficient catalyst to the following reactions:?1?An efficient base-free Chan-Lam coupling reaction using novel Cu???-NHC:the optimal reaction system with novel N-heterocyclic carbene copper as catalyst,an efficient base-free C-N bond formation of arylboronic acids with anilines and imidazoles using novel Cu???-NHC under mild conditions.?2?One-pot synthesis of substituted thiophene and furan derivatives from terminal alkynes:the optimal reaction system with novel N-heterocyclic carbene copper as catalyst,a highly efficient selective synthesis of 2,5-disubstituted furan and2,5-disubstituted thiophene derivatives using terminal alkynes has been developed.This reaction was a convenient and simple pathway for the synthesis of the thiophene or furan derivatives.?3?Suzuki-Miyaura cross-coupling reaction of sterically hindered aryl chlorides with arylboronic acids using novel Pd???-NHC:the optimal reaction system with novel N-heterocyclic carbene palladium as catalyst.It is noticeable that the palladium complex was highly efficient for the synthesis of the substituted biaryls.Conclusion:A series of novel imidazolium ligands with practical value were developed,and a series of new Cu???-NHC,Ag???-NHC and Pd???-NHC were constructed,which further enriched the types of transition metal catalysts.The N-heterocyclic carbene-metal complexes acted an efficient catalyst to base-free Chan-Lam coupling reaction,Suzuki-Miyaura coupling reaction of sterically hindered aryl chlorides with arylboronic acids and high-efficiency synthesis of substituted furan and thiophene derivatives by one-pot method.The method with simple,green and efficient have been developed,and more accord with the concept of“green chemistry”.