Synthesis of 3,3'-Biindoles through a Copper-Catalyzed Friedel-Crafts Propargylation/Hydroamination/Aromatization Sequence.

A copper-catalyzed Friedel-Crafts propargylation/hydroamination/aromatization sequence is described. In the presence of a catalytic amount of CuI, this sequential reaction can convert ethynyl benzoxazinanones and indoles into a diverse set of 3,3'-biindoles with high efficiency and selectivity. Moreover, the synthesis of other indole-heteroaryl molecules and the catalytic asymmetric formation of axially chiral 3,3'-biindoles are demonstrated.