MECHANISTIC ORGANIC PHOTOCHEMISTRY .21. ELECTRONIC DETAILS OF 2,5-CYCLOHEXADIENONE REARRANGEMENT
MECHANISTIC ORGANIC PHOTOCHEMISTRY .21. ELECTRONIC DETAILS OF 2,5-CYCLOHEXADIENONE REARRANGEMENT
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DOI：
10.1021/ja00980a030
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发表时间：
1967-01-01
影响因子：
15
通讯作者：
SWENTON, JS
中科院分区：
文献类型：
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作者：
ZIMMERMAN, HE;SWENTON, JS
4, 4-二苯基环己二烯酮重排为 6, 6-二苯基双环[3.1, 0] hex-3-en-2-one 被证明是一种有效的过程，量子产率为 0.85。量子效率与溶剂无关。获得的证据表明涉及二烯酮三联体。由有效的系间穿越形成的三联体以大于 2 X 1010 sec-1 的速率重新排列。其他结果表明，骨架变化后，三重态降级为基态中间体，然后进一步重新排列形成产物；基态中间体被合理地表述为先前假设的介离子物种。未达到双环酮产物的激发三重态。所观察到的介离子两性离子倾向于生成双环酮而不是恢复为二烯酮，这是在分子轨道基础上理解的。先验可能的 4-3 苯基迁移被证明不会干扰。在二烯酮三重态被萘猝灭的条件下，在 77 K 的玻璃中，二烯酮重排不会发生。光谱证据表明存在-*三重态，而分子轨道考虑表明这是物种重排。高浓度的萘用作单线态敏化剂。
The rearrangement of 4, 4-diphenylcyclohexadienoneto 6, 6-diphenylbicyclo [3.1, 0] hex-3-en-2-one was shown to be an efficient process with a quantum yield of 0.85. The quantum efficiency was solvent independent. Evidence was obtained that the dienone triplet is involved. The triplet, formed by efficient intersystem crossing, rearranges at a rate greater than 2 X 1010 sec-1. Additional results showed that after skeletalchange the triplet demotes to a ground-state intermediate which then rearranges further to product; the ground-state intermediate is reasonably formulated as the mesoionic species postulated earlier. The excited triplet of bicyclic ketone product is not reached. The observed preference of the mesoionic zwitterion to proceed to bicyclic ketone rather than revert to dienone is understood on a molecular orbital basis. The a priori possible 4—3 phenyl migration was shown not to intervene. The dienone rearrangement did not occur at 77 K in a glass under conditions where the dienone triplet was quenched by naphthalene. Spectroscopic evidence showed the presence of the-* triplet, and molecular orbital considerations suggest that this is the species rearranging. Naphthalene in high concentration was used as a singlet sensitizer.