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.