Visible-light-mediated radical reactions of indoles with para-quinone methides using eosin Y as an organophotoredox catalyst

Abstract

Herein, we demonstrate a redox-neutral, operationally simple, atom-economical, and additive-free approach for the synthesis of indolyl diarylmethanes via a radical reaction of indoles with para-quinone methides (p-QMs) under visible-light mediated reaction conditions using eosin Y as an organophotoredox catalyst. This protocol was found to be compatible with a wide range of differently substituted p-QMs and indoles in organic as well as in aqueous media under visible-light irradiation, furnishing the desired products in good to excellent yields.