华中师范大学叶飞团队报道了光促进的芳香脱硝氯化。相关研究成果发表在2025年1月20日出版的《自然—化学》。

硝基芳烃是易于制备的散装化学品，可以作为一系列合成反应的通用起始材料。然而，由于CAr-NO₂键的惰性，与未活化的硝基芳烃的直接脱硝取代反应仍然具有挑战性。化学家依靠顺序还原和重氮化，然后进行Sandmeyer反应或活化硝基芳烃的亲核芳香取代来实现硝基转化。

该文中，研究人员开发了一种在可见光照射下的通用脱氮氯化反应，其中氯自由基通过CAr-NO₂键的断裂取代硝基部分。这种实用的方法适用于各种未活化的硝基（杂）芳烃和硝基烯烃，对空气或水分不敏感，可以在十克标度上顺利进行。

这种转化在合成和机理上与之前在热条件下的，亲核芳香取代反应有着根本的不同。密度泛函理论计算揭示了取代反应的可能途径。

附：英文原文

Title: Light-promoted aromatic denitrative chlorination

Author: Liang, Tiantian, Lyu, Zhen, Wang, Ye, Zhao, Wenyan, Sang, Ruocheng, Cheng, Gui-Juan, Ye, Fei

Issue&Volume: 2025-01-20

Abstract: Nitroarenes are readily accessible bulk chemicals and can serve as versatile starting materials for a series of synthetic reactions. However, due to the inertness of the CAr–NO2 bond, the direct denitrative substitution reaction with unactivated nitroarenes remains challenging. Chemists rely on sequential reduction and diazotization followed by the Sandmeyer reaction or the nucleophilic aromatic substitution of activated nitroarenes to realize nitro group transformations. Here we develop a general denitrative chlorination reaction under visible-light irradiation, in which the chlorine radical replaces the nitro moiety through the cleavage of the CAr–NO2 bond. This practical method works with a wide range of unactivated nitro(hetero)arenes and nitroalkenes, is not sensitive to air or moisture and can proceed smoothly on a decagram scale. This transformation differs fundamentally from previous nucleophilic aromatic substitution reactions under thermal conditions in both synthesis and mechanism. Density functional theory calculations reveal the possible pathway for the substitution reaction.

DOI: 10.1038/s41557-024-01728-1

Source: https://www.nature.com/articles/s41557-024-01728-1