Atroposelective Synthesis of Axially Chiral C2-Arylindoles via Rhodium-Catalyzed Asymmetric C-H Bond Insertion.

A highly efficient rhodium-catalyzed formal C-H insertion reaction between indoles and 1-diazonaphthoquinones has been established, providing a novel protocol for the atroposelective synthesis of axially chiral C2-arylindoles (up to 99:1 er) under mild reaction conditions. Typically, only 1 mol % of Rh 2 ( S -PTTL) 4 is used and the chelation group is not needed for this conversion.