1,2-二基与简单的烯酸的催化性分子间C-化:一个可回收的指导小组策略
Zhiqian Wang1, Brandon J Reinus, Guangbin Dong
1Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, USA.
Journal of the American Chemical Society
|August 15, 2012
概括
这项研究引入了一种新型的催化C-化循环二基使用olefins. 这种高效的方法简化了合成,为创造有价值的化合物提供了更绿色的替代方案.
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:
- 子α-基化是有机合成中的一个基本转变.
- 现有的方法往往需要恶劣的条件或固态测试试剂.
- 开发催化和高效的C-化方法仍然是一个重大挑战.
研究的目的:
- 开发一种新型的催化分子间C-化循环1,2-二基的方法.
- 为了利用简单的终端油脂素作为化剂.
- 为了提高效率和可持续性,雇用一个可回收的指导小组.
主要方法:
- 在周期性1,2-二基和终端烯之间发生催化反应.
- 使用aminopyridine作为可回收的指导组,在现场形成酶胺.
- 乙烯基C-H键的激活和随后的C-化.
- 通过水解裂变并通过导向组的恢复.
主要成果:
- 第一个Rh催化分子间C-化循环1,2-二基与终端烯的例子.
- 已证明广泛的基质范围,包括亚利法性烯酸,芳香性烯酸和乙烯酸.
- 在一个中成功合成3-乙基-5-甲基-1,2-cyclopentadione,产量为53%,显著超过之前的四步路径 (16%的产量).
结论:
- 开发的方法为催化基α-化提供了一种高效和多功能途径.
- 可回收的指导小组战略增强了可持续性和原子经济.
- 这项工作为未来使用未被激活的烯酸进行催化化开发奠定了基础.
相关概念视频
01:22Alkenes via Reductive Coupling of Aldehydes or Ketones: McMurry Reaction
The radical dimerization of ketones or aldehydes gives vicinal diols through a pinacol coupling reaction. However, the behavior of titanium metals used for the reaction as a source of electrons is unusual. When the reaction is carried out in the presence of titanium, diols can be isolated at low temperatures. Else titanium further reacts with diols, forming alkenes through the McMurry reaction.
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Introduction
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.
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.
01:27Aldol Condensation with β-Diesters: Knoevenagel Condensation
The Knoevenagel condensation is an aldol-type reaction involving the condensation of aldehydes or ketones with active methylene compounds such as β-diesters to produce substituted olefins.
02:44Oxidation 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.
01:21Acid-Catalyzed α-Halogenation of Aldehydes and Ketones
By replacing an α-hydrogen with a halogen, acid-catalyzed α-halogenation of aldehydes or ketones yields a monohalogenated product
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
02:04Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
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