Switching between Concerted and Stepwise Mechanisms for Dyotropic Rearrangements of β-Lactones Leading to Spirocyclic, Bridged γ-Butyrolactones
Switching between Concerted and Stepwise Mechanisms for Dyotropic Rearrangements of β-Lactones Leading to Spirocyclic, Bridged γ-Butyrolactones
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DOI：
10.1021/jo2012175
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发表时间：
2011-09-02
影响因子：
3.6
通讯作者：
Tantillo, Dean J.
中科院分区：
文献类型：
--
作者：
Davis, Rebecca L.;Leverett, Carolyn A.;Tantillo, Dean J.
应用量子化学计算（B3LYP/6-31+G(d,p)）来研究螺内酯的向异性重排机制，以评估这些反应是否一致。根据这些计算结果设计的机械实验支持理论得出的结论。特别是，Zn(II)盐或布朗斯台德酸诱导逐步的向变性过程，而由甲硅烷基三氟甲磺酸酯介导的向变性重排是协同过程。用 Zn(II) 盐分离的其他产物支持碳阳离子中间体的逐步过程。此外，还发现了由三环-β-内酯和螺-γ-内酯产生的容易的 Grob 型断裂。
Quantum chemical computations (B3LYP/6-31+G(d,p)) were applied to examine the mechanisms of dyotropic rearrangements of spirolactones in order to assess whether these reactions are concerted. Mechanistic experiments, designed on the basis of the results of these calculations, support the conclusions derived from theory. In particular, Zn(II) salts or Bronsted acids induce stepwise dyotropic processes, whereas dyotropic rearrangements mediated by silyltriflates are concerted processes. Additional products isolated with Zn(II) salts support a stepwise process with a carbocationic intermediate. Furthermore, a facile Grob-type fragmentation emanating from both a tricyclic-P-lactone and a spiro-gamma-lactone was identified.