机械立体化学的开始的结束
1School of Chemistry, University of Birmingham, Birmingham B15 2TT, U.K.
Accounts of chemical research
|June 3, 2024
概括
机械立体化学在罗塔克桑和卡泰南中,以前未被充分探索,现在是可访问的. 新的方法允许选择性合成这些性分子,用于催化和材料科学中的应用.
科学领域:
- 超分子化学 超分子化学
- 有机合成 有机合成
- 立体化学是一种立体化学.
背景情况:
- 自1961年以来,机械互锁分子 (MIM) 的立体化学 (如罗塔克桑和基) 已被确定为它们的功能至关重要.
- 从历史上看,仅从机械键上访问具有立体异构的合MIM仅限于合色谱,阻碍了大规模生产和财产调查.
- 这些分子中的立体单位通常定义不佳,使得现场的进展和问题识别复杂化.
研究的目的:
- 审查MIM中的机械立体化学的历史发展和结构基础.
- 定义和分类的完整套独特的立体单位在两个组成的罗塔克桑和catenanes.
- 总结MIM的立体选择性合成的一般策略,包括所有已识别的机械立体单位.
主要方法:
- 机械立体化学的历史回顾,从1961年最初的识别开始.
- 结构分析和立体化学论证,以识别和分类MIM中所有独特的立体单位.
- 用各种机械立体单元对 [2]catenanes和 [2]rotaxanes进行立体选择性合成的一般合成方法的开发.
主要成果:
- 已明确识别和分类了双组分罗塔克桑和卡泰南的完整的独特立体单位,最后一个将在2024年确定.
- 新的方法可以通过机械立体化学选择性合成MIM,使其可用于各种应用.
- 机械立体单位的性质显著影响立体选择合成策略的选择.
结论:
- 机械立体化学领域随着明确的方法和立体化学概念的发展而成熟.
- 现在可以使用具有高立体纯度的MIM,从而使其在催化,传感和合材料方面的潜力得到探索.
- 已经为MIM在需要精确控制分子形状的应用中发挥功能性作用奠定了基础.
相关概念视频
01:17Thermal Electrocyclic Reactions: Stereochemistry
2.0K
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.
2.0K
01:33Radical Halogenation: Stereochemistry
3.7K
Stereochemistry is the study of the different spatial arrangements of atoms in a given molecule. The stereochemistry of radical halogenations can be understood from three different situations:
Halogenation to form a new chiral center:
Halogenation to form a new chiral center:
3.7K
01:26Photochemical Electrocyclic Reactions: Stereochemistry
1.8K
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
1.8K
01:12Stereochemical Effects of Enolization
2.0K
The chiral α-carbon of the carbonyl compound is the stereocenter of the molecule. As shown in the figure below, when such a carbonyl compound undergoes racemization under an acidic or basic condition, an achiral enol is formed.
2.0K
02:32Stereoisomers
12.8K
On the basis of mirror symmetry, stereoisomers of an organic molecule can be further classified into diastereomers and enantiomers. Diastereomers are stereoisomers that are not mirror images of each other. Substituted alkenes, such as the cis and trans isomers of 2-butene, are diastereomers, as these molecules exhibit different spatial orientations of their constituent atoms, are not mirror images of each other, and do not interconvert. Here, the interconversion is suppressed due to...
12.8K
02:23SN2 Reaction: Stereochemistry
9.5K
In an SN2 reaction, the nucleophilic attack on the substrate and departure of the leaving group occurs simultaneously through a transition state. As the nucleophile approaches the substrate from the back-side, the configuration of the substrate carbon changes from tetrahedral to trigonal bipyramidal and then back to tetrahedral, leading to an inversion in the configuration of the product.
If the substrate is an achiral molecule at the α-carbon, the inversion of configuration is not...
If the substrate is an achiral molecule at the α-carbon, the inversion of configuration is not...
9.5K