环状曲张系统中的环状曲张能量. 应变能量对 [3 + 2] 循环添加反应与亚酸的作用
1Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA. rbach@udel.edu
Journal of the American Chemical Society
|March 24, 2009
概括
这项研究计算了循环基和基的环应变能量和化度. 这些值与循环添加反应障碍相关,为应力环化学提供了洞察力.
科学领域:
- 计算化学是一种计算化学.
- 有机化学 有机化学
- 反应动力学反应动力学
背景情况:
- 环应变显著影响循环有机分子的反应性.
- 了解应变能量 (SEs) 和化 (DeltaH(hyd)) 的度对于预测化学行为至关重要.
- 循环基,基和基因由于环约束而具有独特的结构和能量特性.
研究的目的:
- 为一系列循环基,基和基 (C5-C9) 计算SE和DeltaH(hyd).
- 为了研究SEs,DeltaH(hyd) 与 [3+2]循环添加反应的激活障碍之间的相关性.
- 为了评估替代对cyclooctyne应变能量的影响.
主要方法:
- 利用G3级理论进行高精度的计算计算.
- 计算了各种循环化合物的SE和DeltaH () 值.
- 使用B3LYP/6-311+G(3df,2p) 理论水平的循环加法反应的相关能量参数与计算的激活障碍.
主要成果:
- 确定了环丁 (48.4 kcal/mol),环素 (40.1 kcal/mol) 和环丁 (25.4 kcal/mol) 的SE.
- 对于E-环合 (49.3千卡/mol) 和E-环合 (25.2千卡/mol) 的计算SE.
- 赛克洛克提因的SE值 (19.9 kcal/mol) 比E-赛克洛克提因的SE值 (17.9 kcal/mol) 高.
- 3,3-二环氧化物 (DIFO) 的SE降低了 (17.3 kcal/mol).
- 与非循环对应物相比,压力循环基和基的循环添加激活障碍较低.
- DIFO证明了与化物循环添加的减少激活能量.
结论:
- SEs和DeltaH ((hyd) 是对应力循环系统反应性的有价值的描述器.
- 环应变直接影响 [3+2] 循环加法反应的动力学.
- 替代可以调节循环基因的应变和反应性.
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