Study On Nickel-catalyzed Radical-initiated Three-component Difunctionalization Of Alkynes

The development of new catalytic systems that achieve the regio-selective and stereo-selective construction of olefin compounds has received much attention in synthetic chemistry.Alkynes are cheap and readily available commodities,and the functionalization of alkynes has become an ideal choice for constructing alkenes compounds.In recent years,transition metal-catalyzed bifunctionalization of alkynes has attracted extensive attention.Although important progress has been made in this field,this type of reaction still faces many challenges in the control ofreactivity and selectivity.This dissertation focuses on the nickel-catalyzed bifunctionalization of alkynes,which is mainly divided into the following two parts.Part I:Utiling the nickel-catalyzed radical relayed reductive coupling strategy,we have reported the first example of three-component carbon-fluoromethylation of alkynes and fluorohalomethanes with aliphatic halides by using Ni(BF₄)₂·6H₂O/1,10-phen as catalyst and zinc powder as the reducing agent.The reaction demonstrated good functional group compatibility and substrate applicability,and a series of arylalkyne and enyne substrates can be efficiently converted.To?-fluoromethyl olefin compounds with excellent regioselectivity and stereoselectivity without the use of organometallic reagents.Moreover,merging fluoromethylation with intramolecular radical cyclization of bromo-alkynes led to the construction of a series of CF₂H/CH₂F-incorporated lactones and lactams with high efficiency.This method can be further extended to alkynes,aliphatic halides,that derivatived complex bioactive molecules,further demonstrating the versatility and utility of this protocol.Part II:Utiling photoredox/nickel dual catalysis strategy,we have successfully achieved intermolecular 1,3-alkenyl arylation of saturated cyclic alcohol derivatives and unactivated alkynes with saturated aryl halides to o afford a series of polysubstituted cycloalkanes with moderate yields in the present of Ir(4',6'-d F-5-CF₃-ppy)₂(dtbbpy)PF₆ as photocatalyst,Ni Cl₂(Py)₄as nickel catalyst,dtbbpy as ligand,bis(4-methoxyphenyl)methanone(A)as additive,90W Blue LED as light source.The reaction conditions are mild and functional group compatibility is good,and a series of non-activated alkynes and aryl halides can efficiently obtain polysubstituted cycloalkane compounds.