Research In Nickel-catalyzed Reductive Cross-coupling Of Alkynes,fluoroalkyl Halides,and Vinyl Halides

Due to the unique properties of fluorine atoms,the selective introduction of fluorine atoms or fluorine-containing alkyl groups into organic molecules has always been the focus of attention.In the past few decades,great progress has been made in the direct fluoroalkylation of aromatic compounds.However,there are few reports on the construction of direct fluoroalkylation of olefins,especially mutilsubstituted olefins or dienes.Currently known protocols mainly focus on the cross couplings between alkenyl nucleophiles or electrophiles and fluoroalkylating reagents in two-component system.In recent years,transition-metalcatalyzed fluoroalkylative functionalization of alkynes provides another way to construct fluoroalkylated alkenes,with a simultaneous introduction of another C-C bond,which can quickly increase the complexity and diversity of molecules.At present,most reports focus on the fluoroarylation,fluoroalkynlation and fluorocyanation of alkynes catalyzed by palladium or copper.Similar strategies have not been applied to the nickel-catalyzed fluoroalkenylation of alkynes to construct fluoroalkyl-incorporated dienes.Therefore,it is of great significance to explore the fluoroalkenylation of alkynes catalyzed by the cheap transition metal to construct 1,3-dienes which are widely existing in the structures of drugs and natural products.Based on the nickel-catalyzed free radical addition mechanism,we developed a method for the selective reductive coupling of alkynes with fluoroalkyl halides and vinyl halides to form multisubstituted 1,3-dienes.The mild reaction is operationally simple and avoids the use of organometallic reagents,offering a broad scope and functional group tolerance.Hence,the reaction is compatible with a series of amide,ester and aryl substituted alkenyl halides.Under the optimal conditions,the reaction can achieve moderate to excellent separation yields to afford the single trans-addition mutilsubstituted 1,3-dienes with excellent chemo-,regio-and stereo-selectivity.