了解氧和硫的相对转移活性:过渡状态脱效应的计算分析
1Department of Chemistry, State University at Stony Brook, Stony Brook, New York 11794-3400, USA.
Journal of the American Chemical Society
|November 1, 2001
概括
计算研究表明,在与氨基和卡巴尼昂核的核酸转移反应中,酸的活性明显高于酸,但与氧化物相似. 这种差异归因于电子移位效应.
科学领域:
- 有机化学 有机化学
- 计算化学计算化学
- 反应机制 反应机制
背景情况:
- 氧和硫是有机化学中的关键功能组.
- 了解它们的相对反应性对于合成应用至关重要.
- 核酸转移反应是基本的转换.
研究的目的:
- 通过计算来研究氧和硫的相对反应性.
- 阐明控制核酸转移中的反应性差异的因素.
- 为了比较与各种核友的反应性:氧化物,氨和carbanions.
主要方法:
- 开发关键反应的过渡状态模型.
- 量子力学计算来模拟反应路径.
- 自然键轨道 (NBO) 分析以评估电子移位.
- 过渡状态的债券旋转分析.
主要成果:
- 计算准确地重现了实验反应性趋势.
- 提奥与氧化的氧具有类似的反应性.
- 与氨 (100-fold) 和carbanions (≥2000-fold) 相比,thioesters的反应性明显高于oxoesters.
- 根据NBO的分析,含有氨基/碳素核的氧的脱位化能量损失更大.
结论:
- 反应性的差异是由电子移位能量的不同损失解释的.
- 一个关键的p(X) -->sigma(C-Nu) 相互作用影响了这些系统中的反应性.
- 计算建模为反应性提供了有价值的见解.
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