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首页> 外文期刊>RSC Advances >Theoretical investigations toward the [3+2]-dipolar cycloadditions of nitrones with vinyldiazoacetates catalyzed by Rh-2(R-TPCP)(4): mechanism and enantioselectivity
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Theoretical investigations toward the [3+2]-dipolar cycloadditions of nitrones with vinyldiazoacetates catalyzed by Rh-2(R-TPCP)(4): mechanism and enantioselectivity

机译：用RH-2（R-TPCP）（4）（4）（R-TPCP）（4）（R-TPCP）（4）的vinyldiazoAcetates对亚硝肽的理论研究（4）：机制和对映选择性

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摘要

The mechanism of Rh-2(R-TPCP) 4-catalyzed [3 + 2]-dipolar cycloadditions between vinyldiazoacetate and nitrone to form 2,5-dihydroisoxazole has been studied by ONIOM methodology calculations including density functional theory and semi-empirical PM6 theory. This mechanism begins with carbenoid formation catalyzed by a rhodium catalyst, followed by vinylogous addition/cyclization of an iminium to construct a five-membered ring isoxazolidines, and followed by the functionalization processes of 1,3-hydride abstraction/proton transfer to generate 2,5-dihydroisoxazoles. The calculated results indicate a distinct stepwise fashion of this [3 + 2]-cycloaddition because of the extremely transient intermediate that emerged in the vinylogous reaction, and the cyclization of iminium addition is deemed to be the enantio-controlling step. According to analysis of thermodynamic information, the process of protonation has the highest energy barrier in this catalytic cycle and is determined as the rate controlling step. A higher enantioselective formation of (R)-2,5-dihydroisoxazole derived from the reaction between aryl nitrone and s-trans vinylcarbenoid is evaluated. What's more, we kinetically analyze the enantioselectivity of this complete catalytic cycle by the AUTOF program and provide the reactivity trends with an activation strain model.
机译：通过oniom方法计算研究了vinyldiazo乙酸酯和亚硝酮与形成2,5-二羟基异恶唑之间的rH-2（R-TPCP）4催化的[3 + 2] - Dipolar环加成的机理。包括密度泛函理论和半经验PM6理论。该机制开始于铑催化剂催化的甲骨形成，其次是亚胺的乙烯基加成/环化，以构建五元环异恶唑啉，然后用1,3-氢化物抽取/质子转移的官能化方法进行，以产生2， 5-二羟基异恶唑。计算结果表明，由于在乙烯基反应中出现的极其瞬态的中间体，所以逐步的逐步时尚逐步时尚，并且被认为是氨基化添加的环化是对脑控制步骤。根据热力学信息的分析，质子化过程在该催化循环中具有最高的能量屏障，并确定为速率控制步骤。评估衍生自芳基与S-反式乙烯基甲苯之间反应的（R）-2,5-二羟基异恶唑的较高对映选择性的形成。更重要的是，通过Autof程序动力学分析该完整催化周期的对映射性，并提供具有激活应变模型的反应性趋势。

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  • 来源
    《RSC Advances》 |2016年第59期|共13页
  • 作者

    Ma Ling-Ling; Wang Wan; Wang Gui-Chang;

  • 作者单位

    Nankai Univ Minist Educ Dept Chem Key Lab Adv Energy Mat Chem Tianjin 300071 Peoples R China;

    Nankai Univ Minist Educ Dept Chem Key Lab Adv Energy Mat Chem Tianjin 300071 Peoples R China;

    Nankai Univ Minist Educ Dept Chem Key Lab Adv Energy Mat Chem Tianjin 300071 Peoples R China;

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  • 正文语种 eng
  • 中图分类 化学;
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