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首页> 外文学位 >Practical procedures for the preparation of N-tert-butyldimethylsilylhydrazones and their use in synthetic organic chemistry.
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Practical procedures for the preparation of N-tert-butyldimethylsilylhydrazones and their use in synthetic organic chemistry.

机译：N-叔丁基二甲基甲硅烷基hydr的实用制备方法及其在合成有机化学中的应用。

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摘要

Hydrazones serve as intermediates in numerous reactions of synthetic utility, including such important transformations as the Wolff-Kishner reduction and the Barton vinyl iodide preparation. The synthesis of hydrazones from carbonyl-containing compounds, however, is frequently problematic, and methods that involve hydrazones as intermediates often suffer as a consequence. In this work we develop practical chemistry for the preparation of N-tert -butyldimethylsilylhydrazone (TBSH) derivatives from aldehydes and ketones by condensation with equimolar amounts of 1,2-bis(tert-butyldimethylsilyl)hydrazine (BTBSH) and a catalytic quantity of scandium trifluoromethanesulfonate (typically, 0.01 mol %). We show that these products are formed with higher efficiencies (typically >95% yield) than are simple hydrazones, that they exhibit greatly enhanced stabilities (they can be stored and subjected to routine laboratory manipulations without evident decomposition), and that they undergo a number of synthetically useful transformations. Optimized procedures are provided for the use of TBSH derivatives in a Wolff-Kishner-type reduction protocol that proceeds at low temperature (23--100°C) and in a single reaction flask. Similarly, protocols for the use of TBSH derivatives as precursors to vinyl halides and gem-dihalides are described in detail. These reactions typically proceed in higher yield and under milder conditions than the corresponding transformations employing simple hydrazones as substrates. We also describe a new method for the synthesis of diazoalkanes by the oxidation of TBSH derivatives with (difluoroiodo)benzene, a reagent heretofore unexplored in the context of hydrazone oxidation. When conducted in the presence of a carboxylic acid substrate, the oxidation leads to efficient esterification in situ. In addition to greatly extending the range of diazoalkanes that are now available for esterifications, this new protocol offers significant advantages with regard to safety, for diazo intermediates are neither isolated nor achieve appreciable concentrations during the reaction.
机译：dra在许多合成应用反应中充当中间体，包括沃尔夫-基什纳还原反应和巴顿乙烯碘化物制备等重要转化。然而，由含羰基的化合物合成的方法常常是有问题的，因此，以azo为中间体的方法常常会受到影响。在这项工作中，我们开发了通过与等摩尔量的1,2-双（叔丁基二甲基甲硅烷基）肼（BTBSH）和催化量的condensation缩合反应从醛和酮制备N-叔丁基二甲基甲硅烷基hydr（TBSH）衍生物的实用化学三氟甲磺酸盐（通常为0.01摩尔％）。我们证明，与简单的hydr相比，这些产品的形成效率更高（通常> 95％的产率），它们的稳定性大大提高（可以储存并进行常规实验室操作而没有明显的分解），并且它们经历了多次综合有用的转换。提供了在低温（23--100°C）和单个反应烧瓶中进行的Wolff-Kishner型还原方案中使用TBSH衍生物的优化程序。类似地，详细描述了使用TBSH衍生物作为卤乙烯和卤代二卤的前体的方案。与采用简单than作为底物的相应转化相比，这些反应通常在更高的产率和更温和的条件下进行。我们还描述了通过用（二氟碘）苯氧化TBSH衍生物来合成重氮烷烃的新方法，该试剂迄今为止在in氧化的背景下尚未被开发。当在羧酸底物存在下进行时，氧化导致有效的原位酯化。除了大大扩展了现在可用于酯化的重氮烷烃的范围外，该新方案还具有安全性方面的显着优势，因为重氮中间体在反应过程中既未分离也未达到明显的浓度。

著录项

  • 作者

    Furrow, Michael Enzo.;

  • 作者单位

    Harvard University.;

  • 授予单位 Harvard University.;
  • 学科 Chemistry Organic.
  • 学位 Ph.D.
  • 年度 2004
  • 页码 376 p.
  • 总页数 376
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 有机化学;
  • 关键词

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