切换立体选择性: (fullero) 皮罗利丁"一张牌"
Enrique E Maroto1, Salvatore Filippone, Angel Martín-Domenech
1Departamento de Química Orgánica I, Facultad de Química, Universidad Complutense , E-28040 Madrid, Spain.
Journal of the American Chemical Society
|July 28, 2012
概括
这项研究为具有高反选择性的pyrrolidinofullerenes和pyrrolidines提供了立体分离合成. 富勒伦是开发催化剂的基准,用于控制1,3-双极循环添加中的立体化学结果.
科学领域:
- 有机化学 有机化学
- 超分子化学 超分子化学
- 催化剂是一种催化剂.
背景情况:
- 富勒烯是具有多样化应用的独特的碳异构体.
- 立体选择合成对于开发新型功能分子至关重要.
- 1,3-双极循环添加反应是有机合成中的多功能工具.
研究的目的:
- 为罗利迪诺[3,4:1,2]富勒和相关的罗利迪因开发立体分离合成路径.
- 为了在这些合成中实现高的enantioselectivity.
- 为了利用富勒作为立体控制的1,3-双极循环添加剂中催化剂发展的基准.
主要方法:
- 采用立体选择性的1,3-双极循环加法反应.
- 使用特定的富勒烯衍生物作为反应伙伴.
- 开发和测试用于立体化学控制的新型催化系统.
主要成果:
- 成功地合成了cis/trans pyrrolidino[3,4:1,2].fullerenes的立体分离合成.
- 在内/外罗利丁的合成中获得的高选择性.
- 富勒作为催化剂查和机理学研究的基准证明了它的实用性.
结论:
- 开发的合成策略使得人们可以接触到以酶体丰富的pyrrolidino[3,4:1,2],fullerenes和pyrrolidines.
- 富勒伦为推进立体选择性循环添加剂的催化剂设计提供了一个有价值的平台.
- 这项工作为基于富勒的1,3-双极循环添加的机制提供了洞察力.
相关概念视频
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.
02:36Regioselectivity and Stereochemistry of Hydroboration
A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
01:34Woodward–Hoffmann Selection Rules and Microscopic Reversibility
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...
02:23SN2 Reaction: Stereochemistry
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 observed.
If the substrate is an achiral molecule at the α-carbon, the inversion of configuration is not observed.
02:15SN1 Reaction: Stereochemistry
This lesson provides an in-depth discussion of the stereochemical outcomes in an SN1 reaction.
In the first step of an SN1 reaction, the bond between the electrophilic carbon and the leaving group ionizes to generate the carbocation intermediate. The second step of the mechanism is the nucleophilic attack.
In the formed carbocation, the positively charged carbon is sp2 hybridized with a trigonal planar geometry. As all the three substituents lie on the same plane, a plane of symmetry for the...
In the first step of an SN1 reaction, the bond between the electrophilic carbon and the leaving group ionizes to generate the carbocation intermediate. The second step of the mechanism is the nucleophilic attack.
In the formed carbocation, the positively charged carbon is sp2 hybridized with a trigonal planar geometry. As all the three substituents lie on the same plane, a plane of symmetry for the...
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.