Perturbation of Cope's Rearrangement: 1,3,5-Triphenylhexa-l,5-diene. Chameleonic or Centauric Transition Region?
作者:W. v. E. Doering、Yonghui Wang
DOI:10.1021/ja9908568
日期:1999.11.1
Two types of perturbations of Cope's rearrangement are distinguished by their occupancy of sets of four “active” and two “nodal” positions. A “chameleonic” model of a continuum of chair-like transition regions is defined as extending from two noninteracting allyl radicals at one extreme to cyclohexa-1,4-diyl diradical at the other. Perturbations are analyzed quantitatively in terms of obligatory corrections
Cope 重排的两种类型的扰动的区别在于它们占据四个“活动”和两个“节点”位置的集合。椅子状过渡区连续体的“变色龙”模型被定义为从一个极端的两个不相互作用的烯丙基延伸到另一个极端的环六-1,4-二基双基。根据析出物中共轭相互作用的强制性校正和过渡区模型对扰动进行定量分析,该模型指定了烯丙基上的扰动取代基的稳定能转移,如果占据活性位置,如果占据节点位置,则在二级基团上。当该模型应用于变色龙 2,5-(节点)和 1,4-(活性)二苯基六-1,5-二烯时,与经验降低每个苯基基团的活化焓分别为 -8.7 和 -4.4 kcal mol-1 的结果非常一致。在混合型扰动中,1,3,5-三苯基六-1,5-二烯(1,3-二苯基活性;5-苯基-结...