Photoinduced and Proton-Activated N-Heteroarene-Catalyzed Dioxygen Activation for Benzylic and Allylic Oxidation

Abstract

Photo-oxygenation has emerged as a promising strategy for the efficient synthesis of high-value-added carbonyl compounds through direct elaboration of ubiquitous C–H bonds. However, the conventional reliance on superstoichiometric oxidant, expensive transition metal, or organic photocatalyst with cumbersome synthesis process in light-driven oxygenation processes are often deemed economically unfeasible, thus detracting from the potential application in industries. Herein, we present an organic photosensitizer based on “proton-activation” mode, which could be assembled via the simple protonation of commercially available N-heteroarene with acid. Upon the visible-light irradiation, the proton-activated N-heteroarene features a key energy-transfer process with molecular dioxygen in air to form singlet oxygen facilitating diversified benzylic oxidation and allylic C−H bond oxidation. The observed diverse applicability suggests a generic platform for reaction simplification and accelerated synthetic discovery, which could enable broader applicability and accessibility in aerobic oxidation.