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首页> 外文期刊>Organic Chemistry Frontiers >Chiral bisoxazoline catalyzed decarboxylative aldol reactions between -carbonyl acids and trifluoroacetaldehyde hemiacetals as well as trifluoroacetaldehyde: the mechanism, the origin of enantioselectivity and the role of a catalyst
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Chiral bisoxazoline catalyzed decarboxylative aldol reactions between -carbonyl acids and trifluoroacetaldehyde hemiacetals as well as trifluoroacetaldehyde: the mechanism, the origin of enantioselectivity and the role of a catalyst

机译：手性双恶唑啉催化 - 羰基酸和三氟甲甲醛半缩醛和三氟甲醛之间的脱羧性醛醇反应以及三氟甲甲醛：机制，对映选择性的起源和催化剂的作用

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摘要

Chiral bisoxazoline can catalyze the decarboxylative aldol reactions between -carbonyl acids and trifluoroacetaldehyde hemiacetals as well as trifluoroacetaldehyde but with quite different enantioselectivities, in which the reaction involving trifluoroacetaldehyde hemiacetal results in excellent enantioselectivity (95% ee) while that involving trifluoroacetaldehyde results in poor enantioselectivity (28% ee). To uncover their differences, quantum mechanical calculations together with theoretical methods of global reactivity indexes, QTAIM, NCI and distortion/interaction models were applied to these two reactions; the reaction mechanism, the origin of enantioselectivity and the role of bisoxazoline were investigated in detail. For the reaction with 95% ee, it undergoes the processes of decomposition of trifluoroacetaldehyde hemiacetal, nucleophilic addition, decarboxylation and enol-keto tautomerization of the product, and the nucleophilic addition is the rate- and stereo-determining step. Both the distortion energy and weak intermolecular interactions are responsible for the enantioselectivity. For the reaction with 28% ee, it goes through the processes of nucleophilic addition, decarboxylation and enol-keto tautomerization of the product. Chiral bisoxazoline plays a crucial role in increasing the nucleophilicity of -carbonyl acid in the reaction leading to 95% ee, while such a role is not observed in the reaction resulting in 28% ee. The calculated ee values are in good agreement with the experimental results. The results shown here will provide valuable insights into the understanding of these types of reactions, the design of highly efficient organocatalysts, and related asymmetric reactions.
机译：手性双恶唑啉可以催化 - 羰基酸和三氟甲醛半导体以及三氟甲酰甲醛之间的脱羧醛醇反应，但具有相当不同的对映射性，其中涉及三氟甲甲醛的半血缩醛的反应导致优异的映射性（95％EE），而涉及三氟甲醛导致较差的对映射性（ 28％EE）。为了揭示它们的差异，将量子力学计算与全球反应性指数，qtaim，NCI和失真/相互作用模型的理论方法一起应用于这两种反应;详细研究了反应机制，对映选择性的起源和双子唑啉的作用。对于与95％EE的反应，它经历了产物的三氟甲酰甲醛的分解，亲核加成，脱羧和烯醇酮互联化的过程，亲核添加是速率和立体测定步骤。变形能量和弱分子间相互作用既负责对映选择性。对于28％EE的反应，它通过本产品的亲核加成，脱羧和烯醇酮互联化方法。手性bisoxazoline在将导致95％EE的反应中增加 - 羰基酸的亲核性起作用至关重要的作用，而在反应中未观察到这种作用导致28％EE。计算的EE值与实验结果吻合良好。这里显示的结果将提供有价值的见解，以了解这些类型的反应，高效有机催化剂的设计以及相关的不对称反应。

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  • 来源
    《Organic Chemistry Frontiers》 |2018年第18期|共18页
  • 作者

    Yan Chao-Xian; Zhou Pan-Pan; Yang Fang-Ling; Wu Rui-Zhi; Yang Xing; Yang Fan; Shao Xiangfeng;

  • 作者单位

    Lanzhou Univ Coll Chem &

    Chem Engn Key Lab Nonferrous Met Chem &

    Resources Utilizat State Key Lab Appl Organ Chem 222 South Tianshui Rd Lanzhou 730000 Gansu Peoples R China;

    Lanzhou Univ Coll Chem &

    Chem Engn Key Lab Nonferrous Met Chem &

    Resources Utilizat State Key Lab Appl Organ Chem 222 South Tianshui Rd Lanzhou 730000 Gansu Peoples R China;

    Lanzhou Univ Coll Chem &

    Chem Engn Key Lab Nonferrous Met Chem &

    Resources Utilizat State Key Lab Appl Organ Chem 222 South Tianshui Rd Lanzhou 730000 Gansu Peoples R China;

    Lanzhou Univ Coll Chem &

    Chem Engn Key Lab Nonferrous Met Chem &

    Resources Utilizat State Key Lab Appl Organ Chem 222 South Tianshui Rd Lanzhou 730000 Gansu Peoples R China;

    Lanzhou Univ Coll Chem &

    Chem Engn Key Lab Nonferrous Met Chem &

    Resources Utilizat State Key Lab Appl Organ Chem 222 South Tianshui Rd Lanzhou 730000 Gansu Peoples R China;

    Lanzhou Univ Coll Chem &

    Chem Engn Key Lab Nonferrous Met Chem &

    Resources Utilizat State Key Lab Appl Organ Chem 222 South Tianshui Rd Lanzhou 730000 Gansu Peoples R China;

    Lanzhou Univ Coll Chem &

    Chem Engn Key Lab Nonferrous Met Chem &

    Resources Utilizat State Key Lab Appl Organ Chem 222 South Tianshui Rd Lanzhou 730000 Gansu Peoples R China;

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  • 正文语种 eng
  • 中图分类 有机化学;
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