基于准经典轨迹动力学重新审视狄尔斯-阿尔德反应的（非）同步性概念。
Revisiting the concept of the (a)synchronicity of Diels-Alder reactions based on the dynamics of quasiclassical trajectories.
作者信息
de Souza Miguel A F, Ventura Elizete, do Monte Silmar A, Riveros José M, Longo Ricardo L
机构信息
Instituto De Química, Universidade Federal Do Rio Grande Do Norte, Natal, Rio Grande do Norte, 59072-970, Brazil.
Departamento De Química, CCEN, Universidade Federal Da Paraíba, João Pessoa, Paraíba, 58.059-900, Brazil.
出版信息
J Comput Chem. 2016 Mar 30;37(8):701-11. doi: 10.1002/jcc.24245. Epub 2015 Nov 17.
A number of model Diels-Alder (D-A) cycloaddition reactions (H2C=CH2 + cyclopentadiene and H2C=CHX + 1,3-butadiene, with X = H, F, CH3, OH, CN, NH2, and NO) were studied by static (transition state - TS and IRC) and dynamics (quasiclassical trajectories) approaches to establish the (a)synchronous character of the concerted mechanism. The use of static criteria, such as the asymmetry of the TS geometry, for classifying and quantifying the (a)synchronicity of the concerted D-A reaction mechanism is shown to be severely limited and to provide contradictory results and conclusions when compared to the dynamics approach. The time elapsed between the events is shown to be a more reliable and unbiased criterion and all the studied D-A reactions, except for the case of H2C=CHNO, are classified as synchronous, despite the gradual and quite distinct degrees of (a)symmetry of the TS structures.
通过静态（过渡态 - TS 和内禀反应坐标 - IRC）和动力学（准经典轨迹）方法研究了若干 Diels - Alder（D - A）环加成反应（H₂C=CH₂ + 环戊二烯以及 H₂C=CHX + 1,3 - 丁二烯，其中 X = H、F、CH₃、OH、CN、NH₂ 和 NO），以确定协同机理的（非）同步特征。结果表明，使用诸如过渡态几何结构不对称性等静态标准来分类和量化协同 D - A 反应机理的（非）同步性存在严重局限性，并且与动力学方法相比会得出相互矛盾的结果和结论。事件之间的时间间隔被证明是一个更可靠且无偏差的标准，除了 H₂C=CHNO 的情况外，所有研究的 D - A 反应都被归类为同步反应，尽管过渡态结构的（非）对称程度逐渐且差异明显。
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