Isotope effects and the distinction between synchronous, asynchronous, and stepwise Diels–Alder reactions
作者:Daniel A. Singleton、Brian E. Schulmeier、Chao Hang、Allen A. Thomas、Shun-Wang Leung、Steven R. Merrigan
DOI:10.1016/s0040-4020(01)00354-4
日期:2001.6
variety of symmetrical or nearly symmetrical Diels–Alder reactions are studied by a combination of experimental isotope effects, theoretical calculations, and rate observations. Becke3LYP calculations predicted highly asynchronous transition structures for Diels–Alder reactions of bis(boryl)acetylenes, dialkyl acetylenedicarboxylates, triazolinediones, and dialkyl maleates. Rate observations and kinetic
通过实验同位素效应,理论计算和速率观测的组合研究了各种对称或接近对称的Diels–Alder反应。Becke3LYP计算预测了双(硼基)乙炔,乙炔二羧酸二烷基酯,三唑啉二酮和马来酸二烷基酯的Diels-Alder反应的高度异步过渡结构。速率观测和动力学同位素效应与这些预测一致,尽管在某些情况下对计算结构的实验支持明显不明确。降冰片烯的Diels-Alder逆反应支持协同机制。总的来说,狄尔斯-阿尔德反应似乎只对同步过渡态有很小的偏见。