Carbon-Heteroatom Bond Formation Via Synergistic Nickel/Photoredox Catalysis And Beyond

Synergetic catalysis involving transition metal catalysis and photocatalysis has recently become very attractive as a versatile platform for the construction of previously elusive chemical bonds under very mild conditions.In particular,the ability of photoredox catalysis to generate reactive radical intermediates,and also promote elementary organometallic steps via modulation of the oxidation state of transition metal complexes or energy-transfer-mediated pathways when merged with transition metal catalysis has enabled direct coupling of native nucleophilic partners beyond the scope of classical coupling partners.In this dissertation,we reviewed the recent research discoveries utilizing nickel metellaphotoredox catalysis for carbon-hetereoatom bond formation,and the synthetic methodologies for preparing organophosphorus compounds,urea and carbamates.The main work of this dissertation is divided into two aspects;(1)the construction of C-hetereoatom bond catalyzed by nickel metallaphotoredox catalysis for the synthesis of organophosphorus compounds,(2/3)formation of C-N and C-O bonds for the synthesis of unsymmetrical urea,and carbamates under nickel(II)salt/photoredox catalysis.First,we utilized synergetic catalytic strategy by merging nickel and heterogeneous photocatalysis to accomplish an efficient C-P bond formation reaction for the synthesis of aryl and vinyl phosphine oxides.Impressively,the joint used of a nickel complex and CdS heterogeneous photocatalyst under visible light irradiation delivered diverse array of organophosphorus compounds from easily accessible aryl/vinyl halides and pseudohalogens(OTf)in highly efficient fashion.It is worthy to note that we were able to recycle the CdS photocatalyst for five consecutive times without compromising the reaction efficiency.In addition,we were also able to scale-up the reaction to access the desired products in an efficient fashion.Thus,the use of inexpensive CdS as well as the ability to recycle and scale-up the reaction offers an alternative and competitive synthetic route for the construction of C-P bond to the synthetic community.Second,we developed synergistic ligand-free nickel(Ⅱ)salt/photoredox catalyzed multicomponent reaction for the synthesis of unsymmetrical urea in one-pot for the first time.Most interestingly,the reaction proceeds without the addition of exogenous ligand or base to afford unsymmetrical urea from readily available aryl halides,metal cyanates,and amines under mild reaction conditions in an efficient fashion.This protocol is applicable to both primary and secondary amines as well as chiral amines,and exhibits wide substrate scope with good functional group compatibility.The synthetic application of this protocol was demonstrated by gram scale reaction and late stage functionalization of a bioactive molecule.Finally,we successfully extended this synergistic Nickel/photoredox catalyzed multicomponent reaction for the synthesis of carbamates under relatively mild conditions.We used our dual ligand-free Ni(Ⅱ)salt and iridium photocatalyst under blue LED irradiation to access a series of aryl carbamates from readily accessible aryl bromides,sodium cyante and alcohols in one-pot.Moreover,the alcohols could be employed as solvents or as trapping agents to deliver the corresponding aryl carbamates.Both primary and secondary alcohols participated in the reaction to deliver the desired aryl carbamates in good-to-excellent yields.The utility of this reaction was demonstrated by a gram scale reaction.