COPE REARRANGEMENT REVISITED
COPE REARRANGEMENT REVISITED
复制标题
DOI：
10.1021/ja00754a042
复制
发表时间：
1971-01-01
影响因子：
15
通讯作者：
STOHRER, WD
中科院分区：
文献类型：
--
作者：
HOFFMANN, R;STOHRER, WD
本文研究了使科普重排的活化能为负数的问题。构造了半牛瓦烯的分子轨道及其科普重排的过渡态。然后，不同的取代基模式上的反应物或过渡态的能量的影响进行了评估，重点取代基的环丙烷2-8键的强度和不稳定的AS过渡态轨道的影响。有趣的一般结论是，在这个分子框架中，取代基可能通过影响反应物或产物的稳定性来促进或阻碍反应，就像它们通过影响过渡态一样。特别是强平衡的偏好预测电子供体或受体取代基不对称取代，并降低或提高适当的对称取代的科普重排活化能。
This paper attacks the problem of reducing the activation energy of a Cope rearrangement to a negative number. The molecular orbitals of semibullvalene and the transition state for its Cope rearrangement are constructed. Then the effect of different substituent patterns on the energy of reactant or transition state is evaluated with emphasis on the effect of substituents on the strength of the cyclopropane 2-8 bond and on the destabilizing AS transition state orbital. The interesting general conclusion is that in this molecular framework the substituents are as likely to promote or retard a reaction by influencing the stability of reactant or product as they are by influencing the transition state. Specifically strong equilibrium preferences are predicted for-electron donor or acceptor substituents unsymmetrically substituted, and a lowering or raising of the Cope rearrangement activation energy on appropriate symmetric substitution.