Control elements in dynamically determined selectivity on a bifurcating surface.
Control elements in dynamically determined selectivity on a bifurcating surface.
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DOI：
10.1021/ja802577v
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发表时间：
2008-11-05
影响因子：
15
通讯作者：
Singleton, Daniel A.
中科院分区：
文献类型：
--
作者：
Thomas, Jacqueline B.;Waas, Jack R.;Harmata, Michael;Singleton, Daniel A.
采用产物研究、实验动力学同位素效应、标准理论计算和准经典轨迹计算相结合的方法，研究了3-甲氧基酮基环戊二烯(2)与1，3-二烯Diels-Alder环加成反应中动态确定的产物选择性的机理和性质。这些反应中的低能跃迁结构介于[4π二烯+2π二烯]和[2π二烯+4π二烯]环加成模式之间。这些结构及其双周环性质的准确性得到了实验同位素效应的支持。通过这些过渡结构的轨道可以同时生成[4π二烯+2π二烯]和[2π二烯+4π二烯]环加成产物，并且产物的混合物随二烯结构的不同而不同。分析了影响该选择性的因素。过渡结构的几何形状是预测主要产物的有用指标，但选择性也受到轨道接近产物时能面的形状和轨道如何越过过渡态脊线的指导。
The mechanism and the nature of the dynamically-determined product selectivity in Diels-Alder cycloadditions of 3-methoxycarbonylcyclopentadienone (2) with 1,3-dienes was studied by a combination of product studies, experimental kinetic isotope effects, standard theoretical calculations, and quasiclassical trajectory calculations. The low-energy transition structures in these reactions are structurally balanced between [4πdiene + 2πdienone] and the [2πdiene + 4πdienone] modes of cycloaddition. The accuracy of these structures and their bispericyclic nature is supported by the experimental isotope effects. Trajectories passing through these transition structures can lead to both [4πdiene + 2πdienone] and [2πdiene + 4πdienone] cycloadducts, and the mixture of products obtained varies with the structure of the diene. The factors affecting this selectivity are analyzed. The geometry of the transition structure is a useful predictor of the major product, but the selectivity is also guided by the shape of the energy surface as trajectories approach the products and by how trajectories cross the transition state ridge.
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影响因子：
15
作者：
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通讯作者：
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影响因子：
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作者：
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通讯作者：
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作者：
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