Iridium-Catalyzed Oxidative Heteroarylation of Arenes and Alkenes: Overcoming the Restriction to Specific Substrates

A great challenge in transition metal-catalyzed oxidative Ar-H/Ar-H cross-coupling chemistry is to develop privileged catalytic platforms for overcoming the restriction to specific substrates. Reported herein is a Cp*Ir(III) catalytic platform for the broad C-H ortho-heteroarylation of arenes with up to 16 types of directing groups. The power of the platform is further demonstrated by the (Z)-selective heteroarylation of enamides, which is clearly different from the methods where the catalytic chain begins with the metalation of heteroarene leading to (E)-selective product. Unlike the Rh(III)/Rh(I) catalytic version, the stoichiometric reactions of cyclometalated iridium(III) species with benzothiophene suggest an oxidatively induced reductive elimination involving a high-valent diaryl-iridium intermediate. The catalytic platform overcomes the restriction to specific substrates and would be synthetic chemists' toolbox for the construction of aryl-heteroaryl and vinyl-heteroaryl linkages.