Conformer-Specific Heavy-Atom Tunneling in the Rearrangement of Benzazirines to Ketenimines
Conformer-Specific Heavy-Atom Tunneling in the Rearrangement of Benzazirines to Ketenimines
复制标题
苯并氮杂环重排为烯酮亚胺中的构象特异性重原子隧道效应
DOI：
10.1021/acs.joc.9b02482
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Sander, Wolfram
中科院分区：
文献类型：
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作者：
Schleif, Tim;Mieres-Perez, Joel;Henkel, Stefan;Mendez-Vega, Enrique;Inui, Hiroshi;McMahon, Robert J.;Sander, Wolfram
5-甲氧基-2H-苯并氮杂环丙烷是通过在氩气基质中在低温下将相应的苯基叠氮化物分离并辐照来制备的。尽管计算的活化能为4.9 kcalmol-1[B3 LYP/6-311++G（d，p）]，但在T < 30 K的黑暗中，它会发生扩环反应，生成相应的乙烯酮亚胺。由于这种重排进行的速率常数在10-4s-1的顺序，只表现出浅的温度依赖性，结果被解释在重原子隧穿。四个异构苯并氮杂环丙烷从最初的光解，只有一个可以观察到重排;这种构象特异性的解释是其他潜在的可观察到的重排要么太快或太慢，以检测由于其各自的活化势垒的高度和宽度的差异。
5-Methoxy-2H-benzazirine was prepared via irradiation of the corresponding phenyl azide, isolated in an argon matrix at cryogenic temperatures. It undergoes ring expansion to the corresponding ketenimine in the dark atT< 30 K despite a calculated activation barrier of 4.9 kcal mol–1[B3LYP/6-311++G(d,p)]. Since this rearrangement proceeds with a rate constant in the order of 10–4s–1, exhibiting only a shallow temperature dependence, the results are interpreted in terms of heavy-atom tunneling. Of the four isomeric benzazirines resulting from the initial photolysis, only one can be observed to rearrange; this conformer specificity is explained by the other potentially observable rearrangements being either too fast or too slow to be detected due to the differences in heights and widths of their respective activation barriers.