Exploiting The Application Of Zirconocene Benzyne Complexes In Synthesis Of Benzoborirene And Benzyldiborane

Boron-containingπ-heterocyclics are a class of organic boron compounds which exhibit unique properties.Boron-containing organicπ-conjugated molecules are a combination of"main group organic chemistry of boron-containing compounds"and"π-conjugated systems".Benzoborirenes are isoelectronic to benzocyclopropenyl cations.Although there were many theoretical calculations on benzoborirenes in the early days.However,there were few experimental synthetic studies on benzoborirenes,and most of these structures could only be observed via signals in the Matrix.Until 2018,Bettinger’s group reported a case of benzoboriene stabilized by N-Heterocyclic Carbene（NHC）.Nevertheless,the stability of the adduct was still not ideal.It was decomposed completely in one day at room temperature or dimerized in a few weeks at-35°C.So far,synthesis of a base-free benzoborirene has not been achieved yet.Therefore,it will be a milestone to successfully synthesize and structurally characterize a base-free benzoborirene.Zirconium metallocene reagents are widely used in organometallic chemistry.They can participate in various types of reactions such as cycloaddition,coupling.Among them,diphenylzirconocene reagent is a common precursor of zirconocene benzyne complexes.So far,although there have been systematic reports on the reaction mediateded by zirconocene reagent,there is no research on the reaction of zirconocene benzyne complexes with organoborane reagent.Using Cp₂Zr Ph₂and amino（dibromo）borane,this thesis presented the first successful solution-phase synthesis of a base-free benzoborirene with a yield of 65%.In addition,the synthesis of benzyldiboranes was developed when Cp₂Zr Ph₂reacted with other dihaloborane complexes.Chapter 3 shows the process of exploring the synthesis of benzoborirene.We designed five different synthesis strategies to synthesize benzoborirene.Finally,the benzoboriene was successfully synthesized using Cp₂Zr Ph₂ and amino（dibromo）borane.In addition,we also studied the reaction suitability of zirconocene reagents with different haloboranes.By expanding the synthetic method,a variety of zirconocene semi-ring-opened boron-containing compounds and diboranthene compounds were obtained,and the related structures were characterized by single crystal diffraction.Chapter 4 presents mechanism study and the properties of benzoborienes.At80°C,the diphenyl zirconocene reagent eliminatesβ-hydrogen,and then generates zirconocene benzyne intermediates.Subsequently,it reacts with dibromo-aminoborane to generate zirconocene semi-ring-opened boron-containing compounds,and undergoes aσmetathesis reaction.In addition,we also studied the reaction of benzoboriene with Lewis bases,and the reactions involved in the activation of isonitriles and CO-based small molecules.By activating small molecules,a variety of structures with small molecule insertion were obtained,and the related structures were characterized by single crystal structure.Chapter 5 shows the synthesis and properties of benzyldiboranes.The previous synthetic procedures of benzyldiboranes were usually with toxic reagents,expensive raw materials and catalysts,or complex processes.In this paper,by the method of reacting diphenyl zirconocene with haloboranes,we can synthesize various benzyldiboranes.In addition,we analyzed the reaction mode of zirconocene benzyne complexes with haloboranes.When using dibromoarylborane,diboranthenes can be obtained;using amino（dibromo）borane,benzoborirene can be obtained with a yield of 65%;using dichloroborane,zirconocene semi-ring-opened boron-containing compounds and benzyldiboranes can be obtained.In conclusion,the benzoborirene was successfully synthesized by the reaction of diphenylzirconocene reagent with dibromo-aminoborane,and the reactivity of the synthesized benzoborirene was also studied.On the other hand,benzyldiboranes,diboranthene compounds,zirconocene semi-opened boron-containing compounds were synthesized via adjusting different halogenated borane reagents and reaction conditions.This thesis provides a series of novel methods of benzoborienes,benzyldiboranes,benzoborazepines,diboranthenes,zirconocene semi-ring-opened boron-containing compounds.The synthetic method of these compounds can not only lay a foundation for the subsequent application research,but also can develop more new boron-containingπ-heterocyclic systems.