Ligand-Controlled Catalytic Diastereodivergent Hydro-gem-Difluoroallylation of Cyclopropenes

Despite significant progress in the stereoselective synthesis of polysubstituted cyclopropanes, the catalytic diastereodivergent synthesis of polysubstituted cyclopropanes from cyclopropenes remains challenging. Here, we report a copper-catalyzed diastereodivergent hydro-gem-difluoroallylation of 1,3-disubstituted cyclopropenes with 3,3-difluoroallyl sulfonium salt. By fine-tuning the steric effect of the N-heterocyclic carbene (NHC) ligand, the reaction can selectively produce two diastereoisomers from the same starting materials, thereby providing a convenient route to gem-difluoroallylated cyclopropanes. The synthetic utility of this approach is further demonstrated by diverse transformations of the resulting products, making it an attractive approach for obtaining various fluorinated cyclopropanes of medicinal interest. Density functional theory calculations reveal that both the steric effect of the NHC ligands and the coordination interactions between the copper center and the chelating group on the cyclopropenes are key factors in controlling the diastereoselectivity.