Visible light-mediated polychlorination of alkenes via the dichloromethyl radical generated by chloroform and chlorides

We report a novel visible light-mediated protocol for polychlorination of alkenes by employing commercially available bulk chemicals, chloroform and chlorides. This methodology enables the installation of multiple chlorine atoms into alkene feedstocks in a single step and provides the corresponding chloroalkanes in high yields under mild reaction conditions. Additionally, this transformation tolerates a broad substrate scope of substituted olefins, chlorides and pharmaceutical-derived olefins. Initial mechanism studies suggest that a radical-polar crossover mechanism is primarily involved.