4.2 Photosensitized Dearomatization of (Hetero)Arenes

Abstract Dearomatization reactions constitute a powerful strategy to convert aromatic compounds into three-dimensional scaffolds, which have found wide applications in organic synthesis, medicinal chemistry, and materials science. Distinct from ground-state dearomatization, the photosensitized dearomatization of (hetero)arenes capitalizes on excited-state reactivities, enabling the achievement of thermodynamically disfavoured transformations along with the generation of intriguing scaffolds. This review summarizes recent advances in the photosensitized dearomatization of (hetero)arenes according to the type of (hetero)arene. Mediated by appropriate photosensitizers, a series of (hetero)arenes are engaged in photocycloaddition, difunctionalization, or sensitized reduction.