Studies On Nickel-Catalyzed Reductive Anti-Arylation And Intramolecular Cyanoaddition Of Alkynes

Alkynes are readily available for synthesis,and transition metal-catalyzed difunctionalization of alkynes is one of the most important synthesis methods for the construction of complex molecular frameworks,including polysubstituted olefins.In this way,the carbometalation of alkynes and intramolecular annulation cascade reactions catalyzed by cheap metals have been developed gradually.This pattern enables the successful trans-and cis-difunctionalization of alkynes and the synthesis of a series of carbon rings or heterocyclic compounds.However,unstable boron or zinc reagents greatly limit the application of such reactions,so the direct use of aryl halides is an effective strategy.This thesis has investigated nickel-catalyzed reductive antiarylation of alkynes with an intramolecular selective cyanoaddition cascade reaction,and cyclohexenone compounds with nitrile-containing chiral centers have been synthesized.In this thesis,the arylative cyclization of alkyne-tethered malononitriles with aryl iodine catalyzed by nickel has been studied.This reaction involves Ni(0)oxidative addition with aryl iodide,migration insertion of the alkyne,cis/trans isomerization of alkenyl nickel and selective cyanoaddition in the presence of a reductant.This reaction performed good enantioselectivity and regioselectivity for alkynes,enabling the tolerance of heteroaryl substrates such as pyridine.In addition,iron powder was used as reductant in this reaction,which can not only efficiently fulfill the reduction of Ni(II)in the reaction,but also realize the spontaneous hydrolysis of imine products to ketone.This transformation provide a novel exploration idea for the reductive coupling reactions catalyzed by nickel.In conclusion,the asymmetric conversion of alkynes in the reduction mode is achieved in this thesis,which is an important supplement to the method of malonitriles desymmetrization involving boric acid,and also has certain reference significance for further exploration of the reduction coupling/cyclization reactions involving alkynes.