Nickel-catalyzed Electrochemical Enantioselective Oxidation Reactions

Organic electrochemical synthesis makes the reactants occurred oxidation and reduction reactions by utilizing the transfer of electrons to replace the stoichiometric oxidants and reducing agents.Moreover,the reaction conditions are mild and controllable,green and environmentally friendly,and the process and direction of the reaction can be effectively controlled by adjusting the current and voltage.In addition,the redox potential of transition metal catalysts can be adjusted by changing ligands in the process of electrochemical synthesis.And also,can change the chemical selectivity,stereoselectivity,and regioselectivity of the reaction by modifying the chirality ligand.It provides an efficient and controllable method for achieving high chemical selectivity,regioselectivity,and enantioselectivity in asymmetric electrochemical synthesis.Combining the characteristics of electrochemical and transition metal asymmetric catalysis,this paper designed and studied the catalytic activity and reaction models of the metal nickel in the electrochemical reactions.Furthermore,we respectively realized the asymmetric electrochemical difunctionalization,alkenylation of olefins,and asymmetric electrochemical dehydroamination.In the first chapter,we introduce the progress of asymmetric electrochemistry of transition metal catalysis in recent years.Asymmetric transition metal-catalyzed electrochemistry processes can be divided into electrochemical oxidation reactions and reduction reactions.It provided a novel reaction stand for electrochemical catalysis by combination of transition metals catalysts and chiral ligands,which provided a new way to solve the traditional organic asymmetric electrochemical synthesis.In the second chapter,we studied the chiral metal catalyst which by a combination of the metal nickel and chiral diamine ligands to catalysis the activated alkenes asymmetric difunctionalization and alkenylation with 2-acyl imidazole compounds under the electrochemical environment.The reaction was based on anodic oxidative activation for the controlled liberation of chiral α-keto radical species toward olefins radical addition,allowing switchable intermolecular alkene difunctionalization and alkenylation in a highly stereoselective manner.In addition to acting as proton donors to facilitate H2 evolution at the cathode,the unique properties of alcohol additives play an important role in determining the distinct outcomes for alkene functionalization under electrocatalytic conditions.At last,the difunctional products were derivatized and transformed,we demonstrated the value of this reaction in the synthetic application by successfully synthesizing the(+)-antimycotic imidazole and(-)-N-acetylcolchicinol.In the last chapter,we studied the dehydrogenation coupling of 2-acyl imidazole compounds with secondary amine by nickel metal chiral catalyst under electrocatalytic conditions.These reaction conditions are mild and exhibit a wide substrate range and good functional group tolerance.Then the amination product was effectively transformed into(+)-y-Secret inhibitor,(+)-flamprop-methyl,and(+)-flampropisopropyl.The mechanism study shows that the reaction is through the nickel-bound αketo radical and the aminyl radical species in the catalytic electro-organic synthesis.