Multiple Roles of the Pyrimidyl Group in the Rhodium-Catalyzed Regioselective Synthesis and Functionalization of Indole-3-carboxylic Acid Esters

A regioselective synthesis of indole-3-carboxylic acid esters from anilines and diazo compounds has been realized by making use of the pyrimidyl group-assisted rhodium-catalyzed C-H activation and C-N bond formation. The reaction proceeds under mild conditions, exhibits good functional group tolerance and scalability. Reutilization of the pyrimidyl directing group in the resulting products provided an efficient strategy for further C-7 functionalization of indoles. Moreover, the pyrimidyl moiety could be readily removed as a leaving group to offer various free N-H indoles.