Rh(III)-Catalyzed Synthesis of Isocoumarins via C-H Activation of Phenacyl Phosphoniums with Iodonium Ylides

A phosphonium-assisted C-H cyclization with iodoniumylides has been developed under redox-neutral rhodium(III) catalysis,offering a wide variety of valuable isocoumarins in moderate to goodyields. This transformation proceeds through C-H activation, carbeneinsertion, and nucleophilic addition processes. The reaction occurs un-der a low catalyst loading in a short reaction time and does not requirean oxidant.