• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Synthese de 4,4'-biacridans chiraux et leur utilisation comme photocatalyseurs pour la reduction d'halogenures tertiaires (French text).
【24h】

Synthese de 4,4'-biacridans chiraux et leur utilisation comme photocatalyseurs pour la reduction d'halogenures tertiaires (French text).

机译：4,4'-手性双ac啶的合成及其作为光催化剂用于还原叔卤化物的方法（法文）。

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

This thesis focuses on the synthesis of enantioenriched chiral photocatalysts, the 4,4′-biacridans, and their use for the photoreduction of tertiary halides. In the first part, a synthetic approach was developed to obtain the first photocatalyst, 3,3′,10,10 ′-tetramethyl-9,9′,10,10′ -tetrahydro-4,4′-biacridine. The key step of this synthesis was the preparation of a synthetic intermediate, 2,2 ′-diamino-6,6′dimethylbiphenyl and the resolution of its atropisomers by the formation of diastereomeric salts with enantiopure tartaric acid. Both enantiomers of the chiral photocatalyst were prepared from the corresponding enantiomers of this intermediate and obtained in 92 to 97% ee.; An improved version of the first photocatalyst was developed in the hope of obtaining a higher stereoselectivity in the hydrogen transfer step to the prochiral radical. The same synthetic approach was used to prepare the second photocatalyst, 1,1′,3,3′,10,10 ′-hexamethyl-9,9′,10,10′-tetrahydro-4,4 ′-biacridine in its racemic form. Once again, this practical synthesis involves, a chiral diamine, 2,2′-diamino-4,4 ′,6,6′-tetramethylbiphenyl. The resolution of this intermediate and other advanced intermediates by the formation of diastereomeric salts with different chiral acids was attempted, unfortunately without success.; Consequently, a novel synthetic approach was developed in order to isolate the enantioenriched 2,2′-diamino-4,4′,6,6 ′-tetramethylbiphenyl. This synthetic approach is based on the isolation of diastereoisomers obtained from an asymmetric Ullmann coupling using chiral oxazolines as chiral auxiliairies. The subsequent transformation of the separated diastereoisomers gave us access to the enantiomers of the second chiral photocatalyst with 80 to 92% ee.; The methodology for the photoreduction of tertiary halides using both versions of the chiral photocatalysts is also presented in this work. First, the undesirable non-catalysed reactions were minimised using α-bromo-α-methyl-γ-butyrolactone as substrate. The photocatalytic system in racemic form found to be efficient, as no undesired product was found in the reaction mixture. A better substrate, methyl 2-bromo-2-phenylpropanoate, was used in an attempt to carry out an asymmetric photocatalytic reduction. Unfortunately, no selectivity was observed. Finally, a third substrate, methyl 2-bromo-3,3-dimethyl-2-phenylbutanoate, was also reduced using the second version of the chiral photocatalyst. While efficient photoreduction was once again achieved, no selectivity was observed. In a discussion of our results, various hypotheses are put forward to explain the lack of selectivity of the hydrogen transfer step to a prochiral radical.
机译：本文主要研究对映体富集的手性光催化剂4,4 '-双丙烯酰胺的合成及其在三卤化物的光还原中的应用。在第一部分中，开发了一种合成方法以获得第一种光催化剂3,3 '，10,10 ' -tetramethyl-9,9 '< / super>，10,10 ' -tetrahydro-4,4 '-双cr啶。该合成的关键步骤是制备合成中间体2,2 '-二氨基-6,6 '二甲基联苯，并通过形成二甲苯来拆分其阻转异构体。非对映体盐与对映体纯的酒石酸。手性光催化剂的两种对映体均由该中间体的相应对映体制备，并以92至97％ee获得。为了在向手性自由基的氢转移步骤中获得更高的立体选择性，开发了第一光催化剂的改进形式。使用相同的合成方法制备第二种光催化剂1,1 '，3,3 '，10,10 '-六甲基-外消旋形式的9,9 '，10,10 ' -tetrahydro-4,4 '-双cr啶。再次，这种实际的合成涉及手性二胺，2,2 '-二氨基-4,4 '，6,6 '-四甲基联苯。试图通过与不同的手性酸形成非对映体盐来拆分该中间体和其他高级中间体，不幸的是没有成功。因此，为了分离对映体富集的2,2 '-二氨基-4,4 '，6,6 '-四甲基联苯。该合成方法基于使用手性恶唑啉作为手性助剂，从不对称Ullmann偶联中获得的非对映异构体。分离出的非对映异构体的后续转化使我们获得了第二手性光催化剂的对映体，其ee为80至92％。在这项工作中还介绍了使用两种形式的手性光催化剂光还原叔卤化物的方法。首先，使用α-溴-α-甲基-γ-丁内酯作为底物，可将不良的非催化反应减至最少。发现外消旋形式的光催化体系是有效的，因为在反应混合物中未发现不希望的产物。为了进行不对称的光催化还原，使用了更好的底物2-溴-2-苯基丙酸甲酯。不幸的是，没有观察到选择性。最后，使用第二种手性光催化剂也还原了第三种底物2-溴-3,3-二甲基-2-苯基丁酸甲酯。当再次实现有效的光还原时，未观察到选择性。在讨论我们的结果时，提出了各种假设来解释氢转移步骤对前手性自由基缺乏选择性的情况。

著录项

  • 作者

    Rioux, Elise.;

  • 作者单位

    Universite de Montreal (Canada).;

  • 授予单位 Universite de Montreal (Canada).;
  • 学科 Chemistry Organic.
  • 学位 Ph.D.
  • 年度 2002
  • 页码 336 p.
  • 总页数 336
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 有机化学;
  • 关键词

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