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首页> 外文期刊>RSC Advances >Annuloselectivity and stereochemistry in the sulfa-Staudinger cycloadditions of cyclic imines
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Annuloselectivity and stereochemistry in the sulfa-Staudinger cycloadditions of cyclic imines

机译：环状亚胺的苏福斯托格林环加入中的植物切除和立体化学

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摘要

The annuloselectivity and the stereochemistry in the sulfa-Staudinger cycloadditions of cyclic imines are controlled by the ring size of the cyclic imines. Intrinsically, it is the steric hindrance of cyclic imines that controls the annuloselectivity, as well as the stereochemistry in the [2(s) + 2(i) + 2(i)] annulations. A stepwise [4 + 2] annulation mechanism, which incorporates an intermolecular addition, C=S bond isomerization, and subsequently intramolecular addition, is proposed to explain the different stereochemistry in the [2(s) + 2(i) + 2(i)] annulations. The intermolecular addition is regarded as the key stereo-determining step. Firstly, the C3 and C5 stereochemistry is kinetically controlled by the endo or exo addition of imines to the key zwitterionic 2,3-thiaza-1,4-butadiene-type intermediates, and then the C5 and C6 stereochemistry is thermodynamically controlled by the isomerization of the C=S bond in the zwitterionic endo-or exo-adducts generated from the previous step. The intramolecular addition does not affect the stereochemical outcomes of the [2(s) + 2(i) + 2(i)] annulations.
机译：的annuloselectivity和在环状亚胺的磺胺施陶丁格环加成的立体化学是由环状亚胺的环的大小来控制。本质上，它是控制载环的环状亚胺的空间阻碍，以及[2（s）+ 2（i）+ 2（i）]环化中的立体化学。提出了一种逐步加入分子结肠C = S键异构化和随后分子内加入的逐步[4 + 2]附属机制，以解释[2（s）+ 2（i）+ 2（i）中的不同立体化学）]结束。分子间添加被视为关键立体声确定步骤。首先，C3和C5立体化学通过内部或Exo添加到关键的两性离子2,3-噻唑-1,4-丁二烯型中间体中的内部或exo添加，然后通过异构化热力控制C5和C6立体化学。在前一步骤中产生的两性离子内部或外部加合物中的C = S键。分子内加入不影响[2（S）+ 2（I）+ 2（I）]环化的立体化学结果。

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  • 来源
    《RSC Advances》 |2015年第96期|共10页
  • 作者

    Yang Zhanhui; Xu Jiaxi;

  • 作者单位

    Beijing Univ Chem Technol Fac Sci Dept Organ Chem State Key Lab Chem Resource Engn Beijing 100029 Peoples R China;

    Beijing Univ Chem Technol Fac Sci Dept Organ Chem State Key Lab Chem Resource Engn Beijing 100029 Peoples R China;

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  • 正文语种 eng
  • 中图分类 化学;
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