Oxygen as an oxidant in rhodium(III) catalyzed oxidative C-H/C-H cross-coupling between indoles and oxazoles

A Rh(III)-catalyzed oxidative C-H/C-H cross-coupling between indoles and oxazoles with molecular oxygen as an oxidant has been developed to construct a variety of 2-(indol-2-yl)oxazoles. The chelation-assisted strategy endows this catalytic system with an excellent C2-site selectivity by introducing a pyrimidyl directing group. In addition, polycyclic pyridinium salts are also obtained via Rh(III)-catalyzed C-H activation/cyclization of 2-(indol-2-yl)oxazoles with alkynes.