Study On The Reaction Of Silicon-bridged Diyne With Alkynes And Aryl Halides Mediated By Zirconocene

For the advantages of benzosilole small organic molecules,such as the effective reduction of LUMO energy level by its special ?~*-?~* conjugation system,the improvement of electron affinity in the structure,and the disorder of molecular conformation which can be avoided a rigid ladder-type large ring ?-conjugated structure,the benzosilole has been proved to be a well-established application future in the field of organic electroluminescent materials with its unique optical and electrical properties.Therefore,more researches are needed for novel synthetic method to overcome the difficulties of reaction substrates and conditions.Based on our former research in zirconium chemistry,this paper has first proposed a method which use dimethyl(alkynyl)[2-(alkynyl)phenyl]silane(known as silicon-bridged diyne)as the starting material,with the reaction of Negishi reagent Zr Cp2Bu2 to afford silyl-zirconacyclopentadienes and followed by the [2 + 2 + 2] cycloaddition reaction with alkynes mediated by CuCl.A series of new silafluorene derivates had been synthesized with 55 %—95% moderate to excellent yields.Further derivatization of silafluorene ester groups were studied.Firstly,it got through the reduction with LiAlH4,then bromination with PBr3 and coupling with alkynes via alkynyl lithium.Finally two unreported diyne molecules was gived.The reduction and bromination yields of 2a was 100%,92%,respectively.Coupling reaction with alkynes to give diynes 5a and 5b for the yield of 56%,62,respectively.Hereafter a kind of [2,5-bis(phenylethynyl)-1,4-phenylene]-bis[dimethyl(phenylethynyl)silane]7a was gived as a starting material via two step for the yield of 79%,58%.And its reaction with Negishi reagent was studied and optimized for complete conversion.Following reaction with dimethyl acetylenedicarboxylate was studied.Though pure targer molecule was not separated,the improvement method of this reaction was presented by the analysis and interpretation of the results.Finally,the coupling reaction of aryl halide with silyl-zirconacyclopentadienes which had been afforded before had been studied.The direct coupling method and iodination,t-Buli lithiated indirect method were both tried to carry out this reaction.For the direct method,it is not so satisfactory after the optimization of solvent and temperature.In the indirect method,a new kind of diiodo product 9a of silyl-zirconacyclopentadienes was synthesized for a 92% yield.But after lithiated of t-Buli,this dilithium intermediate was too active and some of side products were found.These results were investigated to strengthen theprimary reaction of the direct method and the activity control of the indirect method.The study in this paper will not only makes contributions to the further synthesis of molecules of benzosilole structure with excellent OLED properties,but also provides a theoretical research for the prospect application of these molecules in OLED field.