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
通过产物研究、实验动力学同位素效应、标准理论计算和准经典轨迹的组合,研究了 3-甲氧基羰基
环戊二烯酮 (2) 与 1,3-二烯的 Diels-Alder 环加成反应中动态确定的产物选择性的机制和性质计算。这些反应中的低能量转变结构在 [4pi(diene) + 2pi(dienone)] 和 [2pi(diene) + 4pi(dienone)] 环加成模式之间结构平衡。这些结构的准确性及其双周环性质得到了实验同位素效应的支持。通过这些过渡结构的轨迹可以导致 [4pi(diene) + 2pi(dienone)] 和 [2pi(diene) + 4pi(dienone)] 环加合物,并且获得的产物混合物随二烯的结构而变化。分析了影响这种选择性的因素。过渡结构的几何形状是主要产物的有用预测器,但选择性也受能量表面形状的指导,当轨迹接近产物时,以及轨迹如何穿过过渡态脊。