• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Chemistry: A European journal >Theoretical investigations on the mechanism of hetero-diels-alder reactions of brassard's diene and 1, 3-butadiene catalyzed by a tridentate schiff base titanium(IY) complex
【24h】

Theoretical investigations on the mechanism of hetero-diels-alder reactions of brassard's diene and 1, 3-butadiene catalyzed by a tridentate schiff base titanium(IY) complex

机译：三齿席夫碱钛（IY）配合物催化Braardard's二烯与1,3-丁二烯异二烯-der醛反应机理的理论研究

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 mechanism of the hetero-Diels-Alder reactions of Brassard's diene and 1,3-butadiene catalyzed by a titanium(IV) complex of a tridentate Schiff base was investigated by DFT and ONIOM methods. The calculations indicate that the mechanism of the reaction is closely related to the nucleophilicity- electrophilicity between diene and carbonyl substrates. A stepwise pathway is adopted for Brassard's diene, and the step corresponding to the formation of the C-C bond is predicted to be the rate-determining step with a free-energy barrier of 8.4 kcal mol-~1. For 1,3-butadiene, the reaction takes place along a one-step, two-stage pathway with a free-energy barrier of 14.9kcalmol-~1. For Brassard's diene as substrate, the OCH_3 and OSi(CH_3)_3 substituents may play a key role in the formation of the transition state and zwitterionic intermediate by participating in charge transfer from Brassard's diene to formaldehyde. The combination of the phenyl groups at the amino alcohol moiety and the ortho-tert-buty1 group of the salicylaldehyde moiety in the chiral tridentate Schiff base ligand plays an important role in the control of the stereoselectivity, which is in agreement with experimental observations.
机译：通过DFT和ONIOM方法研究了三齿席夫碱的钛（IV）配合物催化的布拉萨德二烯和1,3-丁二烯杂狄尔斯-阿尔德反应的机理。计算表明，反应机理与二烯和羰基底物之间的亲核亲电性密切相关。 Brassard's diene采用阶梯式路径，与C-C键形成相对应的步骤被认为是决定速率的步骤，其自由能垒为8.4 kcal mol-1。对于1,3-丁二烯，该反应沿着一步法，两步途径进行，自由能垒为14.9kcalmol-〜1。对于Brassard的二烯为底物，OCH_3和OSi（CH_3）_3取代基可能通过参与从Brassard的二烯到甲醛的电荷转移而在过渡态和两性离子中间体的形成中发挥关键作用。手性三齿席夫碱配体中氨基醇部分的苯基和水杨醛部分的邻-叔丁基的组合在控制立体选择性中起着重要作用，这与实验观察一致。

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