Generation of Hydrides or Hydrogen Radicals for Hydrodehalogenation and Deuterodehalogenation of gem-Dihaloalkenes

Terminal monohaloalkenes are common syntheticfragments used in organic synthesis and are alsofound in many natural products. TheirZ/Estereoi-somers are difficult to physically separate, being apersistent difficulty for functional molecular designand synthesis. Herein, we report complementaryhydride and hydrogen radical generation pathwaysto effectuate hydrodehalogenation and deuterode-halogenation ofgem-dihaloalkenes, producingstereo-defined deuterated or nondeuterated (Z)-and (E)-terminal monofluoroalkenes and (E)-termi-nal monochloroalkenes. Our methods have broad substrate scopes and good functional group toler-ance. Mechanistic studies and density functional the-ory calculations elucidate the stereoselectivity