离子水化使不对称催化中的一般性成为可能:去对称化为P-类固醇三酸衍生物
Chi Liu1,2, Yang Yang2, Wenyang Hong2
1Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Binhai New City, Fuzhou, 350207, P. R. China.
这项研究引入了一种新的非对称催化方法,使用离子水化制造性氧化物和硫化物. 这种方法提高了基质的适应性,扩大了可获得的丰富化合物的范围.
科学领域:
- 有机化学 有机化学
- 催化剂是一种催化剂.
- 立体化学是一种立体化学.
背景情况:
- 不对称的合成需要精确的立体化学转移从催化剂到基质.
- 基质结构变化对开发一般不对称催化方法构成挑战.
- 对于P-类固醇化合物的现有方法通常需要特定的基质修改或苛刻的试剂.
研究的目的:
- 开发一种可适应基质的非对称催化策略,用于P-类固醇三酸氧化物和硫化物.
- 通过避免预装替代剂和危险试剂来克服现有方法的局限性.
- 通过催化剂工程来增强非对称催化剂的普遍性.
主要方法:
- 利用离子水化,一种物理化学现象,进行远程脱对称.
- 调整反应介质中的水/离子比,以控制基质-催化剂预组织.
- 利用水介导的离子相互作用来平衡基质结构变化.
主要成果:
- 成功合成具有高反选择性的P-类固醇三酸氧化物和硫化物.
- 证明基质的适应性,而不需要形替代剂.
- 避免使用格里纳德/有机试剂,提供更温和的替代品.
- 增加了可获得的富含素的P-类固醇化合物的多样性.
结论:
- 离子水化是一种可行的策略,可以在不对称催化中增强基质适应性.
- 在现场精确操纵动态离子水化可以提高催化剂性能.
- 这种方法为催化剂工程提供了一个新的维度,以实现更广泛的基板范围.
更多相关视频
06:31Highly Stereoselective Synthesis of 1,6-Ketoesters Mediated by Ionic Liquids: A Three-component Reaction Enabling Rapid Access to a New Class of Low Molecular Weight Gelators
Published on: November 27, 2015
10:17Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
相关概念视频
Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
Alkynes to Aldehydes and Ketones: Acid-Catalyzed Hydration
Analogous to alkenes, alkynes also undergo acid-catalyzed hydration. While the addition of water to an alkene gives an alcohol, hydration of alkynes produces different products such as aldehydes and ketones.
Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
Regioselectivity and Stereochemistry of Hydroboration
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...
Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
