Palladium-catalyzed regioselective C-2 arylation of 7-azaindoles, indoles, and pyrroles with arenes

A palladium-catalyzed regioselective C-2 arylation of 7-azaindoles, indoles, and pyrroles with arenes has been developed. This study unveils that a critical substrate dependent acid concentration is essential for achieving exclusive C-2 selectivity as well as mono-arylation in pyrroles. Incongruent to the literature, the protocol uses a reduced volume (at least 5 times) of arenes for workable access to C-2 arylated heterocycles.