Copper-Catalyzed Hydrosilylation Of Allenes And Alkynes

Organosilicon compounds are widely used in the fields of organic synthesis,biomedicine and material science due to their unique properties.Therefore,the development of simple and efficient methods for synthesis of organosilicon compounds has attracted intensive attention.In terms of synthetic efficiency and atomic economy,transition metal-catalyzed hydrosilylation of unsaturated carbon-carbon bonds is considered to be one of the most direct and efficient methods for the construction of organosilicon compounds.Among them,the synthesis and application of silicon chiral compounds,including chiral silyl-substituted compounds and chiral silicon-centered compounds,has been a hot and difficult topic in organic synthetic chemistry.Currently,most work on hydrosilylation is still limited to the use of noble metal catalysts,and it is of great scientific values to develop asymmetric catalytic reactions for earth-abundant metal.In this dissertation,our research work focuses on the copper-catalyzed hydrosilylation of allenes and alkynes.The main work could be divided into two parts:Part I:Copper-catalyzed regiodivergent and enantioselective hydrosilylation of allenes.Simultaneous control of regio-and stereoselective hydrosilylation of allenes is a challenge due to multiple reaction sites.The different catalytic systems have been successfully established to catalyze hydrosilylation of allenes,but transition metalcatalyzed asymmetric hydrosilylation have been rarely reported.A copper-catalyzed regiodivergent hydrosilylation of a wide range of terminal allenes is developed.The linear and branched allylsilanes were formed respectively by judicious choice of solvents.Furthermore,branched allylsilanes were obtained with high enantioselectivity with the aid of a C2-symmetric bisphosphine ligand.The dependency of regioselectivity on solvent choice was also discussed via DFT calculation studies.Part II:Enantioselective construction of Si-stereogenic vinylhydrosilanes via copper-catalyzed anti-Markovnikov hydrosilylation of alkynes.The currently developed transition metal-catalyzed asymmetric hydrosilylation of alkynes requires the use of expensive metal catalysts,ligands or complex catalytic systems,and mainly produces Markovnikov hydrosilylation products.Here we reported an unprecedented copper-catalyzed asymmetric anti-Markovnikov hydrosilylation of alkynes with dihydrosilanes for the synthesis of silicon-stereogenic products with good regio-and enantioselectivities.The new process is demonstrated on a diverse of substrates and produces new chiral vinylhydrosilanes via a simple and efficient Cu/(S)TolBINAP catalytic system.The studies for elucidating the origin of the regio-and enantiocontrol were performed by using DFT calculations.In summary,we have achieved high regio-,stereo-,and enantioselective hydrosilylation of allenes and alkynes using copper catalyst,and have precisely constructed a series of allylsilanes,alkenylsilanes,and chiral silicon-stereogenic compounds.