Cu(OTf)2-Catalyzed Insertion of Unactivated Alkynes into C-F Bonds of Benzyl Fluorides.

Cu(OTf)2 catalyzes the insertion of unactivated alkynes into benzylic C-F bonds of benzyl fluorides, providing stereodefined alkenyl fluorides. The reaction tolerates diverse substituents and exhibits high chemoselectivity for C-F bonds over C-Cl and C-Br bonds. Mechanistic studies support a cationic pathway involving benzyl and alkenyl cation intermediates. This method provides a new strategy for catalytic C-F bond functionalization and expands the toolbox for organofluorine synthesis.