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 methods relying on superstoichiometric oxidants, expensive transition metals, or organic photocatalysts with cumbersome syntheses in light-driven oxygenation processes are often deemed economically unfeasible, thus detracting from their potential application in industry. Herein, we present an organic photosensitizer based on a “proton-activation” mode, which could be assembled via the simple protonation of commercially available N-heteroarenes with an acid. Upon 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.