Cyclic (Amino)(Aryl)Nitrenium Cations with Lewis Acidity Controlled by Remote Substituents
作者:Wenqing Wang、Xin Zheng、Leran Zhang、Shunjie Li、Yue Zhao、Xinping Wang
DOI:10.1002/cjoc.202100690
日期:2022.2
N-Heterocyclic nitrogen Lewis acids are important in synthetic chemistry. Stable cyclic (amino)(aryl)nitrenium cations, cyc-1+—cyc-3+, were synthesized by chemical oxidation of aryl azo compounds with different substituents, iPr, H and I, at the para positions of the phenyl group. The excited triplet states of cyc-1+—cyc-3+ abstract H-atoms step by step to generate radical intermediates cyc-1H•+—cyc-3H•+
N-杂环氮路易斯酸在合成化学中很重要。稳定的环状(氨基)(芳基)氮阳离子 cyc-1 + -cyc-3 +是通过在苯基的对位上具有不同取代基i Pr、H 和 I的芳基偶氮化合物的化学氧化合成的。cyc-1 + —cyc-3 +抽象氢原子的激发三重态逐步生成自由基中间体 cyc-1H •+ —cyc-3H •+通过 EPR 光谱和产物 cyc-1H 2+ —cyc- 3H 2+由单晶X射线衍射表征。cyc-1 +物种的路易斯酸度—cyc-3 +是远程取代基依赖性的。Cyc-2 + -cyc-3 + 的酸度比之前报道的基于 LUMO 能量的同类物高得多。亲电性使它们能够与中性路易斯碱 Me 3 P形成路易斯加合物,并获得一个电子以产生中性自由基 cyc-1 • —cyc-3 •。