Copper-catalyzed highly switchable defluoroborylation and hydrodefluorination of 1-(trifluoromethyl)alkynes

CF 2 -containing compounds hold significant potential in drug discovery, organic synthesis, and materials science. However, synthesizing various CF 2 -containing building blocks from a single compound remains challenging. Here, we present a Cu-catalyzed, switchable defluoroborylation and hydrodefluorination of trifluoromethylated alkynes, yielding four types of CF 2 -containing compounds. The chemo- and regio-selective sp 2 /sp 3 1,2-diborylation and sp 2 monoborylation of 1-(trifluoromethyl)alkynes are controlled by adjusting the solvent and ligand quantity. Additionally, altering the base allows selective generation of gem -difluoroalkenes or difluoromethylalkenes. Notably, our method prevents over-defluorination of the CF 3 group on unsaturated C-C bonds during nucleophilic additions, preserving the pharmaceutically valuable CF 2 group. Experimental data and density functional theory (DFT) calculations elucidate the regioselectivities of Cu-Bpin addition and the regulatory role of the ligand in selective deborylation processes. Achieving the modular synthesis of various CF 2 -containing building blocks from a single compound remains a formidable challenge. Herein, the authors present a Cu-catalyzed switchable defluoroborylation and hydrodefluorination of trifluoromethylated alkynes, affording four types of synthetically challenging CF 2 -containing compounds.