通过诱导阿佐基的循环二重化研究的循环德克斯特林复合物的同构变性
1Contribution from the Institute for Theoretical Chemistry and Molecular Structural Biology, University of Vienna, UZAII, Althanstrasse 14, A-1090 Vienna, Austria. bernd.mayer@univie.ac.at
Journal of the American Chemical Society
|July 18, 2001
概括
使用诱导圆形二重化和分子建模研究了带有阿佐的β-环氧德克斯综合体. 不同的客分子在宿主腔内采取不同的方向,影响复杂的结构和可变性.
科学领域:
- 超分子化学 超分子化学
- 计算化学计算化学
- 频谱学是一种光谱学.
背景情况:
- β-cyclodextrins是循环的寡糖,在超分子化学中被广泛用作宿主分子.
- 以染色体 (-N=N-) 为特征的阿佐,由于其独特的电子和结构性质,是有趣的客人.
- 了解主机-客户复杂化对于设计新材料和应用程序至关重要.
研究的目的:
- 为了研究β-cyclopodextrin复合体与2,3-diazabicyclo[2.2.2]oct-2-ene及其基衍生物的溶液结构和共同构成.
- 阐明客体结构对主体腔内的结合模式和形状变异性的影响.
- 评估诱导循环二元论 (ICD) 和计算方法在表征这些复杂物中的预测能力.
主要方法:
- 诱导循环二元化 (ICD) 光谱检测宿主中的客分子的奇拉环境.
- MM3-92力场计算和蒙特卡洛模拟化,以确定低能量的复杂结构.
- 半经验计算来预测计算几何的ICD效应.
- 对于溶解效应的连续性近似.
主要成果:
- 家长的阿佐基 (1) 形成一个侧面导向的复合体,其中乙桥最深处的腔.
- 基替代衍生物 (2) 采用面向复合物,其异基透最深.
- 基因化合物形成了一个比硬质阻碍衍生物更具几何定义的复合物.
- 观察到"适合度"和"适合度"之间的差异.
结论:
- 在β-cyclopodextrin腔内的客体的相对定位高度依赖于它们的分子结构.
- 诱导循环二元化和计算建模是确定宿主-客客复杂协同构成的有效工具.
- 客分子的硬质体积和形状显著影响复合物的结合模式和形状灵活性.
- 在客房综合体中,适合度和紧密度之间的直接相关性并不总是有效的.
相关概念视频
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
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.
01:17Thermal Electrocyclic Reactions: Stereochemistry
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.
01:16Cycloaddition Reactions: Overview
Cycloadditions are one of the most valuable and effective synthesis routes to form cyclic compounds. These are concerted pericyclic reactions between two unsaturated compounds resulting in a cyclic product with two new σ bonds formed at the expense of π bonds. The [4 + 2] cycloaddition, known as the Diels–Alder reaction, is the most common. The other example is a [2 + 2] cycloaddition.
01:28Diels–Alder Reaction Forming Cyclic Products: Stereochemistry
The Diels–Alder reaction is one of the robust methods for synthesizing unsaturated six-membered rings. The reaction involves a concerted cyclic movement of six π electrons: four π electrons from the diene and two π electrons from the dienophile.
00:53Olefin Metathesis Polymerization: Acyclic Diene Metathesis (ADMET)
Acyclic diene metathesis polymerization or ADMET polymerization involves cross-metathesis of terminal dienes, such as 1,8-nonadiene, to give linear unsaturated polymer and ethylene. As ADMET is a reversible process, the formed ethylene gas must be removed from the reaction mixture to complete the polymerization process.
Similar to cross-metathesis, ADMET also involves the formation of metallacyclobutane intermediate by [2+2] cycloaddition of one of the double bonds of a terminal diene with...
Similar to cross-metathesis, ADMET also involves the formation of metallacyclobutane intermediate by [2+2] cycloaddition of one of the double bonds of a terminal diene with...
01:29Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
Diels–Alder reactions between cyclic dienes locked in an s-cis configuration and dienophiles yield bridged bicyclic products.