一个结合了理论和实验研究的高效和快速的泰坦催化3-exo循环的研究
Joachim Friedrich1, Michael Dolg, Andreas Gansäuer
1Institut für Theoretische Chemie der Universität zu Köln, Greinstrasse 4, 50939 Köln, Germany. joachim_friedrich@gmx.de
Journal of the American Chemical Society
|May 12, 2005
概括
泰坦二化物促进了3-exo循环,形成环. 这项研究结合了密度函数理论 (DFT) 和实验,揭示了关键的动力学和热力学因素,显示了转换替代产品的优先形式.
科学领域:
- 有机金属化学 有机金属化学
- 反应机制 反应机制
- 计算化学计算化学
背景情况:
- 二化是有机转化的一个已知的催化剂.
- 极端循环是重要的合成方法.
- 了解反应机制对于催化剂和反应设计至关重要.
研究的目的:
- 为了阐明泰坦介导的3-exo循环的机制.
- 调查环烯形成的动力学和热力学方面.
- 确定这些反应中控制立体选择性的因素.
主要方法:
- 结合了理论和实验方法.
- 梯度校正密度函数理论 (DFT) 计算,特别是BP86方法与密度拟合和三倍泽塔基数组.
- 对于中间体的债券解离能 (BDE) 计算.
- 计算结果与实验产品分布的比较.
主要成果:
- BP86 DFT 方法可靠地模拟了泰坦介导的激素反应.
- 贝塔-泰坦氧基具有与基基相似的热力学稳定性.
- 循环化步骤在热力学上是有利的.
- 立体选择性是由中间稳定性决定的,有利于转换的产品.
- 产品比率与DFT预测保持一致.
结论:
- 泰坦烯介导的3-exo循环是热力学上有利的和立体选择性的.
- 介质稳定性决定了对转换替代环烯产品的偏好.
- 有效地捕获环基基对整体环基的形成至关重要.
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