• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Chemistry: A European journal >New chiral auxiliaries for dynamic kinetic resolution: From theory to experiment
【24h】

New chiral auxiliaries for dynamic kinetic resolution: From theory to experiment

机译：动态动力学拆分的新型手性助剂：从理论到实验

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

New efficient chiral auxiliaries for dynamic kinetic resolution (DKR) of bromides into amines are proposed, based on a theoretical rationalisation of known literature results. One example was synthesized and tested, affording diastereoselectivities up to 100%. Several results of DKR reactions are known, based on oxazolidinone or imidazolidinone units as chiral auxiliaries. Nevertheless, their behaviour was not fully understood until a recent paper that we published. We now used our proposed mechanism to rationalize the behaviour of other similar chiral auxiliaries and to propose small structure changes in imidazolidinone rings which could largely improve their performance. We could show that the good performance of these molecules as chiral auxiliaries for DKR reactions where bromine is the leaving group and a primary or secondary amine is the nucleophile is due, in a first step, to the formation of a hydrogen bond between the amine and the ring carbonyl oxygen and, in a second step, to the strong electrostatic interaction between the leaving bromide and the carbonyl oxygen in the C-3 substituent. Considering the behaviour of this substituent which rotates to minimize the electrostatic repulsion with the bromide when reaching the transition state, we proposed the introduction of a second substituent in the C-4 position of the imidazolidinone ring, which prevents such rotation, thus increasing the energy difference between the transition states of the two distereoisomers. With such an auxiliary we were able to increase the best de known in literature (88%), when benzylamine is used as nucleophile, to 99, or even 100%, when iodide replaces the bromide in the substrate.
机译：基于已知文献结果的理论合理性，提出了一种新的有效的手性助剂，用于将溴化物动态动力学拆分（DKR）转化为胺。合成并测试了一个实施例，其非对映选择性高达100％。基于恶唑烷酮或咪唑烷酮单元作为手性助剂，DKR反应的一些结果是已知的。但是，直到我们发表了一篇最新论文，他们的行为才被完全理解。现在，我们使用我们提出的机制来合理化其他类似手性助剂的行为，并提出咪唑烷酮环中的小结构变化，这可以大大改善其性能。我们可以证明，这些分子作为DKR反应的手性助剂的良好性能，其中溴是离去基团，伯或仲胺是亲核试剂，这首先是由于胺和氢之间形成了氢键环羰基氧，并在第二步中，使剩余的溴化物与C-3取代基中的羰基氧之间的强静电相互作用。考虑到该取代基在达到过渡态时会旋转以使与溴化物的静电排斥最小化的行为，我们建议在咪唑烷酮环的C-4位引入第二个取代基，以防止这种旋转，从而增加能量两个立体异构体的过渡态之间的差异。使用这种助剂，当使用苄胺作为亲核试剂时，我们能够将文献中已知的最佳值（88％）提高到当碘化物替代基质中的溴化物时达到99％，甚至100％。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号