Molecular iodine catalyzed C3-quaternization via oxidative dearomatization of indoles: direct access to 3,3-di(indolyl)indolin-2-ones

Abstract

An efficient and sustainable method for the synthesis of 3,3-di(indolyl)indolin-2-one derivatives has been developed via iodine-catalyzed oxidative dearomatization, where indole alone directly participates in the reaction. Utilising iodine as a green oxidant and DMSO as the optimal solvent, the reaction proceeds under mild conditions, eliminating the need for pre-functionalized indoles and minimising waste, aligning with green chemistry principles. The optimized protocol demonstrates broad substrate scope, high yields, and excellent selectivity, tolerating various functional groups.