Catalysts and ligands possessing the great ability to tolerate over a wide range of mechanistically unrelated reactions are remarked as "privileged", which are rather scarce but extremely meaningful in asymmetric catalysis. Feng and co‐workers have developed a library of conformationally flexible, C₂‐symmetric N,N'‐dioxide amide compounds with original design and featured structure (named as Feng ligand now). They were initially reported as chiral organocatalysts in 2005 and have been further developed as a new class of privileged chiral ligands since 2006. Tremendous success, including versatile coordination chemistry with plenty of metal sources (main‐group metals, transition metals, and rare‐earth metals), a truly broad scope of asymmetric reactions (more than 50 types), diverse areas of catalysis (organocatalysis, Lewis‐acid catalysis, bimetallic relay catalysis, and photocatalysis), numerous synthetic applications of bioactive compounds, has been achieved using Feng N,N'‐dioxide. Besides, they demonstrate that chiral ligands with conformationally flexible property can offer excellent chiral environment as well, which challenges the conventional idea preferring rigid structures in the design of chiral ligands. Herein, we briefly introduced the discovery of Feng ligand and the millstones during the development. We also covered the successful applications of Feng ligand by other scientists as well as novel chiral ligands inspired by them.

中文翻译：

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冯配体：不对称催化的特权手性配体

具有宽泛的耐受各种机械无关反应的能力的催化剂和配体被标记为“有特权的”，这是稀缺的，但在不对称催化中非常有意义。Feng和他的同事们开发了一个构象灵活的C ₂对称N，N库具有原始设计和特征结构的'-二氧化酰胺化合物（现命名为Feng配体）。它们最初于2005年被报道为手性有机催化剂，自2006年以来已被进一步发展为一类新的特权手性配体。取得了巨大的成功，包括具有多种金属源（主族金属，过渡金属和稀土）的通用配位化学金属），Feng N已实现了范围广泛的不对称反应（50多种类型），催化的不同领域（有机催化，路易斯酸催化，双金属中继催化和光催化），生物活性化合物的众多合成应用，N'-二氧化物。此外，他们证明具有构象柔性性质的手性配体也可以提供优异的手性环境，这挑战了在手性配体设计中偏爱刚性结构的传统观念。在此，我们简要介绍了在开发过程中冯配体和磨石的发现。我们还介绍了其他科学家对冯配体的成功应用以及受他们启发的新型手性配体。