N-异环碳酸催化 (4+2) 循环添加/脱碳氧化西二醇乙烯与α,β不和酸化物
Sarah J Ryan1, Lisa Candish, David W Lupton
1School of Chemistry, Monash University, Clayton 3800, Victoria, Australia.
Journal of the American Chemical Society
|March 12, 2011
概括
研究人员开发了一种全新的全碳N-异环碳素催化 (4 + 2) 循环添加. 这种方法有效地合成使用酸化物和西二醇乙烯的1,3-环二烯具有高的二选择性.
科学领域:
- 有机化学 有机化学
- 催化剂是一种催化剂.
- 合成方法论 合成方法论
背景情况:
- N-异环碳 (NHCs) 是多功能器官催化剂.
- 循环添加反应是有机合成的基础.
- 开发用于循环添加的新催化系统仍然是一个关键的挑战.
研究的目的:
- 报告第一个全碳N-异环碳素催化 (4 + 2) 循环添加反应.
- 为了探索与α,β不和酸化物和西二醇乙烯的反应范围.
- 为了证明一个新的反应级联涉及α,β不和酸.
主要方法:
- 使用全碳N-异环碳作为催化剂.
- 采用α,β不和酸化物和西二醇乙烯作为反应伙伴.
- 研究循环添加产品的二选择性.
主要成果:
- 首个全碳NHC催化 (4 + 2) 循环添加的成功开发.
- 在1,3-环环二烯的形成中获得的高二选择性 (dr>20:1) .
- 展示一种利用α,β不和酸的新型反应级联.
结论:
- 这项研究引入了一种新的,高效的有机催化方法,用于合成替代的1,3-环合二烯.
- 开发的方法提供了出色的立体化学控制.
- 这些发现扩大了NHC催化在循环添加反应中的实用性.
相关概念视频
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
Cycloaddition 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.
Electrophilic 1,2- and 1,4-Addition of X2 to 1,3-Butadiene
Electrophilic addition of halogens to alkenes proceeds via a cyclic halonium ion to form a 1,2-dihalide or a vicinal dihalide.
Diels–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.
Diels–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.
Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
Alkenes are converted to 1,2-diols or glycols through a process called dihydroxylation. It involves the addition of two hydroxyl groups across the double bond with two different stereochemical approaches, namely anti and syn. Dihydroxylation using osmium tetroxide progresses with syn stereochemistry.


