在环开放电循环反应中解开不寻常的扭矩选择性:DFT视角
Arpita Poddar1, Jesús Sánchez-Márquez2, Alejandro Morales-Bayuelo3
1Department of Chemistry, Indian Institute of Technology Kharagpur, 721302, India.
Physical chemistry chemical physics : PCCP
|December 10, 2025
概括
本研究使用电子密度分析探索化学反应的立体化学. 它揭示了超越传统模型对预测和控制反应结果的新见解.
科学领域:
- 计算化学计算化学
- 有机反应机制 有机反应机制
- 量子化学 是一个量子化学.
背景情况:
- 了解立体选择性对于合成复杂分子至关重要.
- 基于轨道相互作用的传统模型在预测某些反应结果方面存在局限性.
- perfluoro-3,4-dimethylcyclobutene电环开放呈现了不典型的立体化学结果.
研究的目的:
- 为了研究 perfluoro-3,4-dimethylcyclobutene 在电环开放中的扭矩选择性.
- 阐明和预测非典型的立体化学结果,例如Z,Z同位素的形成.
- 通过超越传统的基于轨道的模型来增强立体控制.
主要方法:
- 密度函数理论 (DFT) 的计算.
- 分子中的原子量子理论 (QTAIM) 分析.
- 压力张量分析.
- 对于局部反应率的索引,桑德森的电子负性等分原理.
- 多重回归分析. 多重回归分析.
- 信息理论描述符.信息理论描述符.
主要成果:
- 研究了反应路径上的电子再分配和结合模式.
- 在全球和本地描述符之间建立了有意义的相关性.
- 获得了对反应模式和立体选择性的更深入的见解.
- 发现了反应路径选择性和分子稳定的电子结构基础.
结论:
- 基于电子密度的方法为了解复杂的反应机制提供了强大的工具.
- 这项研究提供了对扭矩选择性和立体化学控制的更全面的理解.
- 这项工作提升了化学反应中立体化学结果的预测能力.
相关概念视频
01:17Thermal Electrocyclic Reactions: Stereochemistry
2.5K
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
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01:26Thermal and Photochemical Electrocyclic Reactions: Overview
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Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
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01:26Photochemical Electrocyclic Reactions: Stereochemistry
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The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
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02:24Acid-Catalyzed Ring-Opening of Epoxides
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Epoxides that are three-membered ring systems are more reactive than other cyclic and acyclic ethers. The high reactivity of epoxides originates from the strain present in the ring. This ring strain acts as a driving force for epoxides to undergo ring-opening reactions either with halogen acids or weak nucleophiles in the presence of mild acid. The acid catalyst converts the epoxide oxygen, a poor leaving group, into an oxonium ion, a better leaving group, making the reaction feasible. The...
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02:26Base-Catalyzed Ring-Opening of Epoxides
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01:34Woodward–Hoffmann Selection Rules and Microscopic Reversibility
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Electrocyclic reactions, cycloadditions, and sigmatropic rearrangements are concerted pericyclic reactions that proceed via a cyclic transition state. These reactions are stereospecific and regioselective. The stereochemistry of the products depends on the symmetry characteristics of the interacting orbitals and the reaction conditions. Accordingly, pericyclic reactions are classified as either symmetry-allowed or symmetry-forbidden. Woodward and Hoffmann presented the selection criteria for...
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