Organocatalytic Arylation of 3-Indolylmethanols via Chemo- and Regiospecific C6-Functionalization of Indoles

An organocatalytic arylation of 3-indolylmethanols has been established via chemo- and regiospecific C6-functionalization of 2,3-disubstituted indoles, leading to the production of bisindolyloxindoles containing an all-carbon quaternary stereocenter in high yields (up to 99% yield). This reaction not only represents the first catalytic arylation of 3-indolylmethanols using 2,3-disubstituted indoles as aromatic nucleophiles but also serves as a good example of direct catalytic C6-functionalization of indoles, which have been scarcely investigated. Besides, this approach also provides an efficient method to access a biologically important 3,3'-disubstituted oxindole framework and a 3',6-linked bisindole skeleton. Furthermore, the investigation of the activation mode suggested that the dual activation of an ion pair and H-bond between the substrates and the catalyst cooperatively contributed to the success of the reaction.