Palladium(II)‐Catalyzed Enantioselective Arylation of Unbiased Methylene C(sp3)−H Bonds Enabled by a 2‐Pyridinylisopropyl Auxiliary and Chiral Phosphoric Acids,Angewandte Chemie International Edition

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Palladium(II)‐Catalyzed Enantioselective Arylation of Unbiased Methylene C(sp3)−H Bonds Enabled by a 2‐Pyridinylisopropyl Auxiliary and Chiral Phosphoric Acids
Angewandte Chemie International Edition ( IF 16.1 ) Pub Date : 2018-06-19 , DOI: 10.1002/anie.201804197
Sheng-Yi Yan ₁ , Ye-Qiang Han ₁ , Qi-Jun Yao ₁ , Xing-Liang Nie ₁ , Lei Liu ₁ , Bing-Feng Shi _{1,

2}

Affiliation

Enantioselective functionalizations of unbiased methylene C(sp³)−H bonds of linear systems by metal insertion are intrinsically challenging and remain a largely unsolved problem. Herein, we report a palladium(II)‐catalyzed enantioselective arylation of unbiased methylene β‐C(sp³)−H bonds enabled by the combination of a strongly coordinating bidentate PIP auxiliary with a monodentate chiral phosphoric acid (CPA). The synergistic effect between the PIP auxiliary and the non‐C₂‐symmetric CPA is crucial for effective stereocontrol. A broad range of aliphatic carboxylic acids and aryl bromides can be used, providing β‐arylated aliphatic carboxylic acid derivatives in high yields (up to 96 %) with good enantioselectivities (up to 95:5 e.r.). Notably, this reaction also represents the first palladium(II)‐catalyzed enantioselective C−H activation with less reactive and cost‐effective aryl bromides as the arylating reagents. Mechanistic studies suggest that a single CPA is involved in the stereodetermining C−H palladation step.

中文翻译：

钯（II）催化的2-吡啶基异丙基辅助和手性磷酸促成的无偏亚甲基C（sp3）-H键的对映选择性丙烯酸化

金属插入对线性系统的无偏亚甲基C（sp ³）-H键的对映选择性官能化本质上具有挑战性，并且仍然是一个尚未解决的问题。在本文中，我们报道了由强配位的双齿PIP助剂与单齿手性磷酸（CPA）结合使用可实现钯（II）催化的无偏亚甲基β-C（sp ³）-H键的对映选择性芳基化。PIP辅助剂与非C ₂剂之间的协同作用对称的CPA对于有效的立体声控制至关重要。可以使用多种脂族羧酸和芳基溴化物，以高收率（高达96％）和良好的对映选择性（高达95：5 er）提供β-芳基化的脂族羧酸衍生物。值得注意的是，该反应还代表了钯（II）催化的第一对映选择性CH活化，其反应性和成本效益较低的芳基溴化物用作芳基化试剂。机理研究表明，单一CPA参与立体确定CH pal的步骤。

更新日期：2018-06-19

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