Synergistic-Catalysis-Enabled Reaction of 2-Indolymethanols with Oxonium Ylides for the Construction of 3-Indolyl-3-Alkoxy Oxindole Frameworks.

A synergistic-catalysis-enabled reaction of 2-indolymethanols with oxonium ylides has been established that makes use of a three-component reaction between 3-diazooxindoles, alcohols, and 2-indolymethanols under the cooperative catalysis of a metal complex and a Brønsted acid. This reaction has not only provided a new approach for the construction of 3-indolyl-3-alkoxy oxindole scaffolds by utilizing the C3-electrophilicity of an indole, but it is also the first example of a nucleophilic addition of a metal-associated ylide to 2-indolylmethanols. In addition, this reaction also includes a rarely reported trapping of onium ylides with aryl electrophiles.