超越罗杰·布朗重排:在合聚氨酸中进行远程原子拓化
John Mabry1, Richard P Johnson
1Department of Chemistry, University of New Hampshire, Durham, New Hampshire 03824, USA.
Journal of the American Chemical Society
|May 30, 2002
概括
在1,3-butadiynes中长距离碳原子拓化首次被观察到. 闪光真空热解诱导了碳原子之间的标签平衡,揭示了原子交换过程并支持了一种新的重新排列机制.
科学领域:
- 有机化学 有机化学
- 物理化学 物理化学
- 计算化学计算化学
背景情况:
- 1,3-Diyne系统是有机合成的基本组成部分.
- 了解碳原子重新排列机制对于预测反应性至关重要.
- 之前的研究已经在相关系统中探索了有限的碳杂乱.
研究的目的:
- 为了演示和描述长距离的碳原子拓化在一个1,3-diyne.
- 通过实验和计算方法阐明碳原子交换的机制.
- 调查潜在的重新排列中间体的能量格局.
主要方法:
- 合成一种13C丰富的1--4-p-多-1,3-丁丁前体.
- 在受控温度 (800-900°C) 和压力 (0.01 Torr) 下进行闪光真空热解 (FVP).
- 核磁共振 (NMR) 光谱用于 (13) C 标签分布分析.
- 密度函数理论 (DFT) 和莫勒-普莱塞特扰动理论的计算.
主要成果:
- 在800°C观察到C-1和C-2之间的几乎完整的 (13)C标签平衡.
- 在900°C时, (13) C标签的显著迁移到C-3和C-4.
- 实验证据证明了碳原子交换过程的内部和内部结合.
- 计算支持一个涉及布朗重排,试烯形成和维尼利丁中间体的机制.
- 烯被确定为具有显著的二基性质的低中间体.
结论:
- 通过热重新排列,可以在1,3-diynes中实现远程碳原子拓化.
- 内部原子交换的激活障碍低于内部原子交换.
- 涉及三烯和维尼利丁中间体的拟议机制准确地描述了观察到的拓化.
- 计算数据为拟议反应途径的能量和可行性提供了关键的见解.
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