Bronsted Acid-Catalyzed Substitution Reactions of 2-Indolyl-methanols with Tryptophols: Chemoselective Synthesis of 2,2-Bisindolylmethanes

A Bronsted acid-catalyzed substitution reaction of 2-indolylmethanols with tryptophols has been established, which afforded a series of 2,2'-bisindolylmethanes in high yields (up to 98% yield) with chemoselectivity. This protocol not only provides an efficient method for constructing biologically important 2,2'-bisindolylmethane frameworks, but also has realized a substitution reaction of 2-indolylmethanols, which will enrich the chemical property of 2-indolylmethanols. Moreover, this approach has utilized the C(2)-nucleophilicity of tryptophols, which provided a good example for controlling the chemoselectivity in tryptophol-involved reactions.