Selective Functionalization Of Alkenes Enabled By Ni/Photoredox Dual Catalysis

Alkenes are widely used in organic synthesis as important starting materials.The nickel-catalyzed dicarbofunctionalization of alkenes can rapidly build up structurally complex and valuable molecules by installing two carbon motifs through vicinal addition across unsaturated hydrocarbons.The traditional methods are largely focused on the reactions of organohalides and organometallic nucleophiles with alkenes.However,the application of this strategy is limited due to the high activity of organometallic reagents.The dicarbofunctionalization of alkenes by two different electrophiles can circumvent the employment of organometallic reagents.Nevertheless,stoichiometric amount of reductants are required,thus leading to new concerns.In recent years,dicarbofunctionalization of alkenes enabled by Ni/photoredox strategy by using radical precursors instead of traditional organometallic nucleophiles has attracted much attention of chemists due to its redox neutral and mild conditions as well as good functional group tolerance.However,compared with the well-developed simplex nickel catalytic system,the Ni/photoredox dual catalytic system is still in its infancy and there are many problems in this field that need to be studied.For example,the varieties of the radical precursors were limited,only secondary and teritary alkyl radicals could be involved in the dicarbofunctionalization process.Moreover,because of the initiating by radical addition,the sole regioselectivity impede further development of the reaction.Therefore,it is of great significance to expand the varieties of radical and realize the DCF of alkenes of different selectivity.In this thesis,selective functionalization of alkenes was studied.Part I: With initiated by radical addition,the 1,2-alkylarylation of alkenes enabled by Ni/photoredox dual catalysis was realized by using α-silylamines as the primary alkyl radical precursor and aryl halide as electrophilic reagent.The key of this reaction is that the introduction of nitrogen atom at the α-position of the primary alkyl radical can increase the stability and nucleophilicity of the radical.In addition,the cascade reaction proceeds under mild,base-free and redox-neutral conditions with good functional group tolerance,and importantly,provides an efficient and concise method for the synthesis of structurally valuable α-aryl substituted γ-amino acid derivatives motifs.Part II: The 2,1-alkylarylation of alkenes enabled by Ni/photoredox dual catalysis was realized by using α-silylamines and aryl halides as dicarbofunctional reagents.By utilizing the ligand effect,the regioselectivity of the reaction was completely reversed and a series of β-amino acid derivatives were synthesized.The reaction with mild conditions and good functional compatibility,which can be used for the late-stage modification of natural products and drug molecules.Moreover,the ORL-1 receptor antagonist can be synthesized by this reaction in one step.The mechanise studies showed that the reaction was tandem migatory insertion and electrophilic trapping.The α-silylamine serves as both reductant and masked electrophile in this reaction.Part III: In this study,the Ni/photoredox dual catalyzed regioselective hydroaminoalkylation of alkenes was realized by initiating the reaction with migratory insertion of Ni H to the olefin.The regioselectivity of the reaction was completely opposite to that previously reported.In this hydroaminoalkylation process,the α-silylamines were served as both reductant and aminoalkyl source.In addition,the remote hydroaminoalkylation of alkenes can be achieved by the “chain-walking” of Ni H.