Theoretical Study Of Transition-metal Catalyzed Coupling Reactions To Construct C-C And C-Si Bond

C-C bonds and C-Si bonds are ubiquitous chemical bonds in the framework of organic molecules,and their construction methods have attracted the attention of chemists.The transition metal catalyzed coupling reaction to construct C-C bond and C-Si bond is a more efficient synthesis method.However,the transition metal catalyzed coupling reaction process is often complicated and the internal mechanism of the reaction is not clear enough.Therefore,the mechanism exploration of the transition metal-catalyzed coupling reaction has become one of the research hotspots of scientific researchers.With the development of computational methodology,computational power and software,computational chemistry is increasingly being used to study experimental phenomena,predict reaction selectivity,and infer the reaction mechanisms.The combination of theoretical study and experimental research was used to solve some of the specific relative trends of reaction.The use of computational chemistry provides scientists with a deeper understanding in comparison with any other existing methods.With the help of the advantages of Computational chemistry,this thesis discusses the mechanism of the formation of C-C bond and C-Si bond in transition metal-catalyzed coupling reactions.Meanwhile,we studied the reactivity of some ligands and substrates,and analyzed some sources of reactivity.The content of this thesis mainly includes the following three parts:(1)The density-functional calculations of M11-L were used to study the mechanism of zinc-catalyzed oxidative coupling of terminal alkynes with benzaldehyde to form carbon-carbon bonds.We proposed the mechanism of mononuclear and dinuclear zinc in this study,and the calculation results show that the binuclear zinc pathway is more favorable than the mononuclear zinc pathway.This conclusion may also be used in other reactions of this type to provide a new idea for designing new catalysts for future experiments.At the same time,we also compared the reactivity of other aldehydes and ketones in the oxidation reaction,and the calculation results show that the oxidants containing electron-deficient carbonyls show higher oxidative properties.(2)The mechanism of palladium-catalyzed bis-silanylation for the formation of carbon-silicon bonds was studied by density functional theory.The mechanism of this reaction often involves carbeneization,oxidative addition,insertion and reductive elimination of silyl groups,and the order of occurrence of carbeneization and oxidative addition is uncertain.The theoretical calculation results show that the reaction is firstly more inclined occurs carbeneization,and then go through the oxidation addition process.In the theoretical exploration of this reaction,we also considered the effects of ligands in the reaction.And the caculation results show that the catalytic carbene bis-silylation reaction involving triphenylphosphine is less active.(3)The density-functional calculations of M11-L were used to study the mechanism of nickel-catalyzed coupling reaction of oxazoles with aryl halides to construct carbon-carbon bonds.The calculation results show that the fluorine anion-coordinated nickel species as a starting catalyst can promote the whole reaction.Advantageous routes for this reaction include:F~-ion assisted oxidation addition,deprotonation,and reduction elimination.Among them,oxidation addition is a rapid control step.