Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, Heidelberg 69120, Germany.
Department of Chemistry, University of Toronto, 80 St. George Street, Toronto M5S 3H6, Canada.
J Am Chem Soc. 2021 Sep 29;143(38):15845-15851. doi: 10.1021/jacs.1c07905. Epub 2021 Sep 15.
A series of catecholato phosphonium ions, including the first stable bis(catecholato)-substituted derivatives, are isolated and fully characterized. The cations rank among the most potent literature-known Lewis acids on the Gutmann-Beckett and ion affinity scales. In contrast to halogenated or multiply charged phosphorus cations, Lewis superacidity is imparted by structural constraints, as disclosed by energy decomposition analysis. The modular access provides a tunable scaffold while maintaining extreme affinity, demonstrated by the synthesis of a chiral Lewis superacid. The combination of electrophilic phosphorus and basic oxygen substituents leverages new reactivity modes by phosphorus-ligand cooperativity. With this, a phosphorus-mediated C-H bond activation is accomplished.
一系列儿茶酚鏻离子，包括第一个稳定的双（儿茶酚）取代衍生物，被分离并进行了全面的表征。在古特曼-贝克特和离子亲和尺度上，这些阳离子是文献中已知的最强的路易斯酸之一。与卤代或多电荷磷阳离子不同，路易斯超强酸性是由结构限制赋予的，这一点通过能量分解分析得到了揭示。模块化的方法提供了一个可调谐的支架，同时保持了极端的亲和力，这一点通过手性路易斯超强酸的合成得到了证明。亲电磷和碱性氧取代基的结合通过磷配体协同作用，利用了新的反应模式。通过这种方式，实现了磷介导的 C-H 键活化。
