Perturbations by Phenyl on the 1,5-Hydrogen Shift in 1,3(<i>Z</i>)-Pentadiene. Another Chameleonic Transition Region?
作者:William von E. Doering、Edmund J. Keliher、Xin Zhao
DOI:10.1021/ja040106k
日期:2004.11.1
The acyclic 1,5-dienyl hydrogen shift is accelerated by radical-stabilizing phenyl substituents without regard to the type of position occupied in the 1,3(Z)-pentadiene system. 1-Phenyl-5-p-tolyl-1,3(Z)-pentadiene has a corrected energy of activation 5.8 kcal mol(-)(1) lower than that of the parent, while the 2- and 3-phenyl analogues, examined in cyclic systems specifically designed to obviate the
无论在 1,3(Z)-戊二烯系统中占据的位置类型如何,自由基稳定化苯基取代基都会加速无环 1,5-二烯基氢位移。1-Phenyl-5-p-tolyl-1,3(Z)-pentadiene 的校正活化能比母体低 5.8 kcal mol(-)(1),而 2- 和 3-苯基类似物,在专门设计用于避免对直接前体 s-cis 构象进行热化学校正的其他一般需求的循环系统中进行检查,分别揭示了 3.6 和 3.4 kcal mol(-)(1) 的稳定作用。这些相对较小的影响与过渡区域的变色龙概念方案一致。