Ga(OTf)3-Catalyzed Temperature-Controlled Regioselective Friedel-Crafts Alkylation of Trifluoromethylated 3-Indolylmethanols with 2-Substituted Indoles: Divergent Synthesis of Trifluoromethylated Unsymmetrical 3,3'-and 3,6'-Bis(indolyl)methanes.

An unprecedented Ga(OTf)3-catalyzed, temperature-controlled regiodivergent alkylation of 2-substituted indoles with trifluoromethylated 3-indolylmethanols is described that provides structurally diverse unsymmetrical 3,3'- and 3,6'-bis(indolyl)methanes with a CF3-containing quaternary carbon center in good to excellent yields under mild conditions. In addition, this present protocol could be successfully extended to the synthesis of difluoromethylated 3,3'- and 3,6'-bis(indolyl)methanes with excellent efficiency.