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首页> 外文期刊>RSC Advances >Revisiting oxime–nitrone tautomerism. Evidence of nitrone tautomer participation in oxime nucleophilic addition reactions
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Revisiting oxime–nitrone tautomerism. Evidence of nitrone tautomer participation in oxime nucleophilic addition reactions

机译：重新审视肟 - 硝基互变异物。硝石互旋剂参与肟亲核加成反应的证据

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The oxime–nitrone tautomerism has been revisited using high-level DFT calculations. The isomerization has been found to be more favorable through a bimolecular process involving two molecules of oxime, a finding that argues against the commonly accepted thermal 1,2-H-shift mechanism. The reaction of arylamidoximes with 1,2-diaza-1,3-dienes to yield the corresponding O -substituted oximes (stable intermediates for the synthesis of 1,2,4-oxadiazine derivatives) was also investigated as a rare case in which O -alkylation is observed in the reaction between oximes and electron-poor alkenes in the absence of a base. Under such conditions the reaction usually proceeds through the nucleophilic attack of the oxime nitrogen to yield the corresponding nitrone. The computational investigation revealed that in the case of arylamidoximes, the pathway involving the less stable but more reactive nitrone tautomer is the predominant mechanism, evidencing for the first time the involvement of a nitrone tautomer in nucleophilic additions of oximes. Validation of the model has been carried out by studying alternative ene-like processes; the dramatically different reactivity predicted for arylamidoximes and unsubstituted oxime are rationalized in terms of steric hindrance.
机译：使用高水平DFT计算已重新审视肟 - 亚硝织物互补性。已经发现异构化通过涉及两个肟分子的共分子过程更有利，该发现是针对常用的热1,2-H型换档机制来争论的发现。还研究了芳氧基与1,2-Diaza-1,3-二烯的反应，得到1,2- diaza-1,3-二烯，得到相应的o-取代的肟（稳定的1,2,4-恶二嗪衍生物的中间体）作为唯一的情况在没有碱基的情况下在肟和电子贫烯烃之间的反应中观察到 - 烷基化。在这样的条件下，反应通常通过肟氮的亲核侵蚀来产生相应的亚硝石。计算研究表明，在芳基酰胺氧基的情况下，涉及稳定但更具反应性赤孔互变异构体的途径是主要机制，首次发挥亚硝基互构体在肟的亲核添加中的累积。通过研究替代的eNE的过程来进行模型的验证;对芳基氧基氧基和未取代的肟预测的大幅不同的反应性是在空间障碍方面合理化。

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