Excited-State S N Ar Reactions of Nitroarenes

Nucleophilic aromatic substitution (SNAr) traditionally requires ground-state dearomatization to form Meisenheimer intermediates, restricting the reactivity to arenes bearing strong electron-withdrawing groups (EWGs). Here we disclose excited-state SNAr reactions of nitroarenes under visible light irradiation, in which triplet-state electronic reorganization furnishes a strong aromaticity-recovery driving force for CAr–NO2 substitution, enabling reaction pathways that are inaccessible in the ground state. Following computational evaluation of common nucleophiles, we developed a synthetically practical protocol that enables denitrative substitution across diverse polycyclic arenes. These findings demonstrate that photoexcitation can reshape the aromatic character of arenes, thereby offering a new strategy to access previously inaccessible modes of arene functionalization.