Savchuk Mariia, Bocquin Lucas, Albalat Muriel, Jean Marion, Vanthuyne Nicolas, Nava Paola, Humbel Stéphane, Hérault Damien, Clavier Hervé
Aix Marseille Univ, CNRS, Centrale Marseille, iSm2, Marseille, France.
Chirality. 2022 Jan;34(1):13-26. doi: 10.1002/chir.23378. Epub 2021 Nov 5.
From achiral imidazolinium salts, chiral transition metal complexes containing an N-heterocyclic carbene (NHC) ligand were prepared (metal = palladium, copper, silver, gold, rhodium). Axial chirality in these complexes results from the formation of the metal-carbene bond leading to the restriction of rotation of dissymmetric N-aryl substituents about the C-N bond. When these complexes exhibited a sufficient configurational stability, a resolution by chiral high-performance liquid chromatography (HPLC) on preparative scale enabled isolation of enantiomers with excellent enantiopurities (>99% ee) and good yields. A study of the enantiomerization barriers revealed the effect of the backbone nature as well as the type of transition metal on its values. Nevertheless, the evaluation of palladium-based complexes in asymmetric intramolecular α-arylation of amides demonstrated that the ability to induce an enantioselectivity cannot be correlated to the configurational stability of the precatalysts.
由非手性咪唑啉鎓盐制备了含有N-杂环卡宾（NHC）配体的手性过渡金属配合物（金属 = 钯、铜、银、金、铑）。这些配合物中的轴手性源于金属-卡宾键的形成，导致不对称N-芳基取代基围绕C-N键的旋转受到限制。当这些配合物表现出足够的构型稳定性时，通过制备规模的手性高效液相色谱（HPLC）进行拆分能够分离出对映体纯度优异（>99% ee）且产率良好的对映体。对映体异构化能垒的研究揭示了主链性质以及过渡金属类型对其值的影响。然而，对钯基配合物在酰胺的不对称分子内α-芳基化反应中的评估表明，诱导对映选择性的能力与预催化剂的构型稳定性无关。
