Lewis Acid and Substituent Effects on the Molecular Mechanism for the Nazarov Reaction of Penta-1,4-dien-3-one and Derivatives. A Topological Analysis Based on the Combined Use of Electron Localization Function and Catastrophe Theory.
Lewis Acid and Substituent Effects on the Molecular Mechanism for the Nazarov Reaction of Penta-1,4-dien-3-one and Derivatives. A Topological Analysis Based on the Combined Use of Electron Localization Function and Catastrophe Theory.
复制标题
路易斯酸和取代基对 Penta-1,4-dien-3-one 及其衍生物 Nazarov 反应分子机制的影响。
DOI：
10.1021/ct7000304
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发表时间：
2007
影响因子：
5.5
通讯作者：
J. Andrés
中科院分区：
文献类型：
--
作者：
V. Polo;J. Andrés
在B3LYP/6-31G(D)计算水平上，结合电子局域化函数和突变理论提供的拓扑分析，我们可以沿着五-1，4-二烯-3-酮和八个衍生物的纳扎罗夫重排的分子机理，考察路易斯酸(质子化H(+)和BH_3的存在)以及α和β位置上的电子给体取代基(-OCH_3)的作用。通过ELF结构稳定域(SSD)的变化来监控反应的进展，每个变化都由CT得出的一个转折点控制。这些SSD和相应的转折点与一系列基本化学步骤相关联。沿着五-1，4-二烯-3-酮的环化路径，表征了四个SSD和三个转折点(Cusp1-Fold1-Cusp2)。第一和第二SSD分别对应于C-O键的极化和C-C键之间的电子重新分布，并且它们可以与氧烯丙基结构的形成相关联。可以将第三个和第四个SSD分配给环关闭过程。氧原子的质子化将反应直接转移到第二个SSD，极大地降低了活化能和反应能。根据ELF盆地布居的介观结构的计算，Lewis酸和电子给体取代基的电子效应被合理化。刘易斯酸与α和β-OCH_3取代基结合，分别在活化能和反应自由能上产生协同和竞争效应。
The joint use of the topological analysis provided by the electron localization function (ELF) and catastrophe theory (CT), at the B3LYP/6-31G(d) calculation level, allows us to examine the Lewis acid (protonation H(+) and presence of BH3) and the role of an electron donor substituent (-OCH3) at α and β positions along the course of the molecular mechanism for the Nazarov rearrangement of penta-1,4-dien-3-one and eight derivatives. The progress of the reaction is monitored by the changes of the ELF structural stability domains (SSDs), each change being controlled by a turning point derived from CT. These SSDs and the corresponding turning points are associated with a sequence of elementary chemical steps. Along the cyclization path of penta-1,4-diene-3-one, four SSDs as well as three turning points (cusp1-fold1-cusp2) have been characterized. The first and second SSDs correspond to a polarization of the C-O bond and electronic redistribution among the C-C bonds, respectively, and they can be associated with the formation of an oxyallyl structure. The third and fourth SSDs can be assigned to the ring closure process. Protonation of the oxygen atom shifts the reactive directly into the second SSD, greatly reducing the activation and reaction energies. The electronic effects due to Lewis acids and electron donor substituents have been rationalized in terms of calculations of mesomeric structures from ELF basin populations. The combination of Lewis acids together with α and β -OCH3 substitutions renders a cooperative and competitive effect on activation and reaction free energies, respectively.