Mechanism and Selectivity Investigation of [Cu]/[Pd] Synergistic Catalyzed Borylfluoroallylation of Alkyne: A DFT Study

Transition-metal-catalyzed fluorination of organic compounds is the most effective method to obtain high-value fluorinated compounds that are widely used in the fields of medicine and materials science. In this work, the synergistically catalyzed mechanism of borylfluoroallylation of acetylene catalyzed by [Cu]/[Pd] bimetallic catalysts as well as the chemoselectivity and regioselectivity of the reactions were investigated by means of density functional theory calculations. The results showed that the whole reaction involves three processes: [Cu]-catalyzed borylcuprization of alkynes and [Pd]-catalyzed open-loop coupling of difluorocyclopropane, followed by transmetalation and reduction elimination of the two intermediates to yield the final product. For the title reaction, the mode of Cu-B bond insertion into the alkyne determines the regioselectivity, while the modes of open-loop coupling of difluorocyclopropane and beta-F elimination control the chemoselectivity. The reduction elimination process is the rate-determining step, yielding cis-a-Pro as the major product. Our work clarifies the catalytic mechanism responsible for acetylene borylfluoroenylation catalyzed by [Cu]/[Pd] catalysts, providing a detailed explanation for reported experimental results and valuable information for acetylene functionalization.