Excited-State SNAr Reactions of Nitroarenes
Zhen Lyu1, Tiantian Liang2, Gui-Juan Cheng1
1Warshel Institute for Computational Biology, School of Medicine, The Chinese University of Hong Kong, Shenzhen 518172, P. R. China.
Abstract:
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.
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