Ruthenium-Catalyzed Oxidative Dearomatization of Indoles for the Construction of C2-Quaternary Indolin-3-ones

Abstract

A ruthenium-catalyzed oxidative dearomatization of 2-alkyl- or 2-aryl-substituted indoles has been developed. When coupled with a cascade transformation, it provides a new system for the construction of indolin-3-ones bearing a C2-quaternary functionality. The reaction occurs readily with RuCl3·3H2O as a catalyst in acetonitrile. 2-(3-Indolyl)-substituted indolin-3-ones were obtained in medium to high yields. A mechanism for the reaction is also proposed.