Development of Ferrocene-Based Planar Chiral Imidazopyridinium Salts for Catalysis,Organometallics

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Development of Ferrocene-Based Planar Chiral Imidazopyridinium Salts for Catalysis
Organometallics ( IF 2.5 ) Pub Date : 2020-06-30 , DOI: 10.1021/acs.organomet.0c00312
Keegan P. Fitzpatrick ₁ , C. Benjamin Schwamb ₁ , Christopher T. Check ₁ , Ki-Po Jang ₁ , David N. Barsoum ₁ , Karl A. Scheidt ₁

Affiliation

Imidazol-2-ylidenes and their N,N′-diaryl derivatives constitute an important class of N-heterocyclic carbenes (NHCs) which possess a unique level of versatility in both organocatalysis and transition-metal catalysis. However, there remain few examples of carbenes of this type that are chiral. Here we describe the development of a family of closely related imidazopyridine-based NHCs that derive their asymmetry purely from planar chirality through the incorporation of the classic metallocene framework. An NMR analysis of ⁷⁷Se complexes of this family is used to assess their degrees of σ donicity and π acidity in comparison to a larger family of NHCs. Percent buried volume (%V_bur) calculations were performed to measure the steric bulk of this distinct class of NHCs. Additionally, these NHCs were employed in various enantioselective transformations to survey their use as organocatalysts as well as ligands for transition-metal-catalyzed processes.

中文翻译：

二茂铁基平面手性咪唑并吡啶鎓盐催化用盐的开发

咪唑-2-亚烷基和它们的N，N'-二芳基衍生物构成一类重要的N-杂环卡宾（NHC），在有机催化和过渡金属催化方面均具有独特的多功能性。但是，几乎没有这种手性的卡宾实例。在这里，我们描述了一个紧密相关的基于咪唑并吡啶的NHC家族的发展，这些家族的不对称纯粹是通过结合经典的茂金属骨架从平面手性中获得的。与较大的NHC家族相比，该家族的^77个Se配合物的NMR分析用于评估其σ酸度和π酸度。埋入体积百分比（％V _bur）进行了计算，以测量这种独特类别的NHC的空间体积。此外，这些NHC被用于各种对映选择性转化中，以调查其作为有机催化剂以及过渡金属催化过程的配体的用途。

更新日期：2020-07-27

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