• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Chemistry: A European journal >Probing the Diastereoselectivity of Staudinger Reactions Catalyzed by N-Heterocyclic Carbenes
【24h】

Probing the Diastereoselectivity of Staudinger Reactions Catalyzed by N-Heterocyclic Carbenes

机译：N-杂环卡宾催化的施陶丁格反应的非对映选择性

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

The reaction of ethylphenylketene with 1,3-dimesitylimidazol-2-ylidene (IMes) or 1,3-dimesitylimidazolin-2-ylidene (SIMes) afforded the corresponding azolium enolates in high yields. The two zwitterions were fully characterized by various analytical techniques. Their thermal stabilities were monitored by thermogravimetric analysis and the molecular structure of SIMesEtPhCCO was determined by means of X-ray crystallography. A mechanism was proposed to account for the trans-diastereoselectivity observed in the [2+2] cycloaddition of ketenes and N-protected imines catalyzed by N-heterocyclic carbenes and an extensive catalytic screening was performed to test its validity. The steric bulk of the NHC catalyst markedly affected the cis/trans ratio of the model -lactam product. The nature of the solvent used to carry out the Staudinger reaction also significantly influenced its diastereoselectivity. Conversely, the nature of the substituent on the N-sulfonated imine reagent and the reaction temperature were less critical parameters.
机译：乙基苯基乙烯酮与1,3-二甲并咪唑啉-2-亚烷基（IMes）或1,3-二甲并咪唑啉-2-亚烷基（SIMes）的反应以高收率提供了相应的烯醇氮盐。这两种两性离子已通过各种分析技术充分表征。通过热重分析监测其热稳定性，并通过X射线晶体学测定SIMesEtPhCCO的分子结构。提出了一种机制来解释在N-杂环卡宾催化的烯酮和N-保护的亚胺的[2 + 2]环加成中观察到的反式-非对映选择性，并进行了广泛的催化筛选以测试其有效性。 NHC催化剂的空间体积显着影响模型内酰胺产品的顺式/反式比。用于进行施陶丁格反应的溶剂的性质也显着影响其非对映选择性。相反，N-磺化亚胺试剂上取代基的性质和反应温度不是关键参数。

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