碳水化合物基的乙烯和乙烯的轻微Pummerer-like反应,其中包括线性臭氧化酸盐作为假定中间体
Natacha Veerapen1, Stephanie A Taylor, Charles J Walsby
1Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6.
Journal of the American Chemical Society
|January 5, 2006
概括
这项研究探讨了含有和硫的碳水化合物异循环中的Pummerer重排. 研究人员发现了一种新的,更温和的合成路径,用于Pummerer产品,涉及激进中间体.
科学领域:
- 有机化学 有机化学
- 碳水化合物化学 碳水化合物化学
- 异环化学 异环化学
背景情况:
- 默尔重组是有机合成中的一个关键反应.
- 在含的异环环中研究Pummerer重排是新.
- 碳水化合物支架为化学转换提供了独特的结构特征.
研究的目的:
- 为了研究含有和硫的碳水化合物基异循环中的Pummerer-like重排.
- 编制Pummerer重排在烯热环中的第一份报告.
- 探索这些重新安排的机制,包括激进与协调的途径.
主要方法:
- 含硫和的碳水化合物异循环的臭氧分解.
- 在低温下添加乙无水化物,以捕获臭氧化物中间体.
- 隔离和反应的中间体氧化物和硫氧化物.
- 激进的诱捕实验使用rubrene.
- 使用DMPO激素陷进行电子磁共振 (EPR) 研究.
主要成果:
- 在臭氧溶解过程中形成了不稳定的臭氧化物中间体.
- 默尔重组产品是通过在低温下添加乙 anhydride 加入臭氧化混合物来获得的.
- 孤立的氧化物和硫氧化物也经历了Pummerer重组,尽管硫氧化物需要更高的温度.
- 有证据表明,重新排列是通过基质中间体进行的,而不仅仅是异质的.
- 确定了一种新的,更温和的方法来产生Pummerer类型的产品.
结论:
- 在基于碳水化合物的烯热循环中,可以有效地实现Pummerer重组.
- 反应机制可能涉及激素中间体,得到了捕获和EPR研究的支持.
- 这项工作为Pummerer产品合成提供了一种新的,更温和的合成方法.
相关概念视频
Preparation of Diols and Pinacol Rearrangement
Compounds bearing two hydroxyl groups are known as diols. When the hydroxyl groups are located on adjacent carbon atoms, the diols are called vicinal diols or glycols. Under acidic conditions, vicinal diols undergo a specific reaction called pinacol rearrangement.
The reaction begins with transferring a proton from the acid catalyst to one of the hydroxyl groups, producing an oxonium ion.
The reaction begins with transferring a proton from the acid catalyst to one of the hydroxyl groups, producing an oxonium ion.
Acid Halides to Carboxylic Acids: Hydrolysis
Hydrolysis of acid halides is a nucleophilic acyl substitution reaction in which acid halides react with water to give carboxylic acids. The reaction occurs readily and does not require acid or a base catalyst.
As shown below, the mechanism involves a nucleophilic attack by water at the carbonyl carbon to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen π bond along with the departure of a halide ion. A final proton transfer step yields carboxylic acid...
As shown below, the mechanism involves a nucleophilic attack by water at the carbonyl carbon to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen π bond along with the departure of a halide ion. A final proton transfer step yields carboxylic acid...
Acid Halides to Esters: Alcoholysis
Alcoholysis is a nucleophilic acyl substitution reaction in which an alcohol functions as a nucleophile. Acid halides react with alcohol to produce esters. The mechanism proceeds in three steps:
Cationic Chain-Growth Polymerization: Mechanism
The cationic polymerization mechanism consists of three steps: initiation, propagation, and termination. In the initiation step of the polymerization process, the π bond of a monomer gets protonated by the Lewis acid catalyst, which is formed from boron trifluoride and water. The protonation of the π bond generates a carbocation stabilized by the electron‐donating group. In the propagation step, the π bond of the second monomer acts as a nucleophile and attacks the generated carbocation,...
Olefin Metathesis Polymerization: Ring-Opening Metathesis Polymerization (ROMP)
Ring-opening metathesis polymerization or ROMP involves strained cycloalkenes as starting materials. The mechanism of ROMP proceeds by reacting cycloalkene with Grubbs catalyst to give metallacyclobutane intermediate which undergoes a ring-opening reaction to form new carbene. The new carbene reacts with another molecule of cycloalkene. Repetition of these steps leads to the formation of an unsaturated open-chain polymer product. All these steps are reversible, however, relieving the ring...
Reactions of Carboxylic Acids: Introduction
Carboxylic acids possess an acidic –COOH functional group. The acidity can be attributed to the resonance stabilization of their conjugate base, wherein the negative charge is delocalized over both oxygen atoms.
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