Through‐Space, Lone‐Pair Promoted Aromatic Substitution: A Relay Mechanism Can Beat Out Direct Activation
Through‐Space, Lone‐Pair Promoted Aromatic Substitution: A Relay Mechanism Can Beat Out Direct Activation
复制标题
通过空间、孤独、配对促进芳香取代：中继机制可以击败直接激活
DOI：
10.1002/chem.202301550
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Tantillo, Dean J.
中科院分区：
文献类型：
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作者：
Kazim, Muhammad;Feng, Zhitao;Vemulapalli, Srini;Siegler, Maxime A.;Chopra, Anant;Minh Nguyen, Phuong;Gargiulo Holl, Maxwell;Guan, Liangyu;Dudding, Travis;Tantillo, Dean J.
我们报道了卤素、四氮唑、非手性酯和酰胺对整个空间芳烃活化的详细的实验和理论分析。与先前假定的通过σ络合物稳定的直接活化相反，我们的结果表明这些反应是以一种新的机制进行的，即含孤对活化剂与亲电的硝酸根离子形成放热的π-络合物，然后通过低势垒过渡态将其转移到探针环上。非共价相互作用图(NCI)和分子中原子的量子理论(QTAIM)分析表明，Lewis碱(LB)与前络合物和过渡态中的硝酸根离子之间存在良好的相互作用，这表明在整个机理中基团的参与是直接的。取代的区域选择性也与接力机制相一致。总而言之，这些数据为亲电芳香取代(EAS)反应的替代平台铺平了道路。
We report a detailed experimental and theoretical analysis of through‐space arene activation with halogens, tetrazoles and achiral esters and amides. Contrary to previously assumed direct activation through σ‐complex stabilization, our results suggest that these reactions proceed by arelaymechanism wherein the lone pair‐containing activators form exothermic π‐complexes with electrophilic nitronium ion before transferring it to the probe ring through low barrier transition states. Noncovalent interactions (NCI) plots and Quantum Theory of Atoms in Molecules (QTAIM) analyses depict favorable interactions between the Lewis base (LB) and the nitronium ion in the precomplexes and the transition states, suggesting directing group participation throughout the mechanism. The regioselectivity of substitution also comports with a relay mechanism. In all, these data pave the way for an alternate platform of electrophilic aromatic substitution (EAS) reactions.