Transition Metal-catalyzed C-F Bond Cleavage Reaction

Due to the extremely large bond energy of the C-F bond,the research on the fracture of the carbon-fluorine bond has been extremely challenging.In recent years,with the vigorous development of transition metal catalysis,the transition metal catalyzed carbon-fluorine bond cleavage reaction has made remarkable achievements,but the carbon-fluorine bond cleavage reaction catalyzed by transition metals still has great limitations,such as the use of expensive the late transition metals palladium,platinum,or iridium,or expensive and inaccessible ligands are used,so it is necessary to further develop new methods for carbon-fluorine cleavage reactions using inexpensive metals under mild conditions.In this work,a new type of C-F bond cleavage functionalization is proposed using cheap and readily available early transition metals such as copper or iron.The Cu-catalyzed perdefluorination of propargyl gem-difluoride substrates and the iron-catalyzed defluoroalkylation of allenyl C-F compounds to obtain tetra-substituted allenes have been successively developed.Work 1: Under the action of a catalytic amount of Cu H,the difluoroalkynyl compound undergoes a carbon-fluorine bond cleavage carbon-carbon triple bond migration reaction,which expands the scope of the cheap transition metal-catalyzed C-F bond cleavage reaction of difluoroalkynes.This reaction system uses a cheap copper catalyst,and the reaction conditions are relatively mild.With good functional group compatibility,difluoroalkynyl compounds with various substituents can be smoothly reacted and converted into the corresponding defluorination products in moderate to good yields.Work 2: Under the action of a catalytic amount of Fe,the defluoroalkylation of monofluoroalkenes and Grignard reagents is carried out,which expands the scope of the C-F bond cleavage reaction of monofluoroalkenes catalyzed by inexpensive transition metals.This reaction system uses an inexpensive iron catalyst,and the reaction conditions are relatively mild.With good functional group compatibility,monofluoroalkenyl compounds of various substituents can be smoothly reacted and converted into corresponding defluoroalkylated products in moderate to good yields.