Achiral CpxIr(III)/Chiral Carboxylic Acid Catalyzed Enantioselective C–H Amidation of Ferrocenes under Mild Conditions,ACS Catalysis

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Achiral CpxIr(III)/Chiral Carboxylic Acid Catalyzed Enantioselective C–H Amidation of Ferrocenes under Mild Conditions
ACS Catalysis ( IF 11.3 ) Pub Date : 2020-06-12 , DOI: 10.1021/acscatal.0c02049
Lei Liu ₁ , Hong Song ₁ , Yan-Hua Liu ₁ , Le-Song Wu ₁ , Bing-Feng Shi ₁

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Ir(III)-catalyzed enantioselective C–H activation generally relies on the combination of chiral Ir(III) cyclopentadienyl complexes with chiral carboxylic acids to ensure high enantiocontrol. We report herein the achiral Cp^xIr(III)-catalyzed enantioselective C–H amidation of ferrocenes. Crucial to the high enantioselectivity is the use of a chiral carboxylic acid ligand derived from tert-leucine via Pd(II)-catalyzed γ-C(sp³)–H arylation and a sterically more hindered Cp^xIr(III) catalyst. This reaction proceeds smoothly under very mild conditions (0 °C) and tolerates a wide range of ferrocene carboxamides and dioxazolones, providing the amidation products in good yields with high enantioselectivity (up to 97.5:2.5 er). This protocol might open the way for achiral Cp^xIr(III)-catalyzed asymmetric C–H activation.

中文翻译：

手性Cp ^x Ir（III）/手性羧酸在温和条件下催化二茂铁的对映选择性C–H酰胺化

Ir（III）催化的对映选择性C–H活化通常依赖于手性Ir（III）环戊二烯基配合物与手性羧酸的结合，以确保对映体的高度控制。我们在此报告了二茂铁的非手性Cp ^x Ir（III）催化的对映选择性CH酰胺化反应。高对映选择性的关键是使用叔亮氨酸通过Pd（II）催化的γ-C（sp ³）-H芳基化和空间位阻更大的Cp ^x衍生的手性羧酸配体Ir（III）催化剂。该反应可在非常温和的条件下（0°C）顺利进行，并能耐受各种二茂铁羧酰胺和二恶唑酮，从而以高收率和高对映选择性（高达97.5：2.5 er）提供酰胺化产物。该协议可能为非手性Cp ^x Ir（III）催化的不对称CH活化开辟道路。

更新日期：2020-07-02

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