两氨基化物重新引导阿扎-迈克尔反应
1Davenport Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada M5S 3H6.
Journal of the American Chemical Society
|October 28, 2009
概括
稳定的二元氨基化物与不和化物发生多米诺反应,形成新的化合物. 这一发现突出了两分子在化学合成和反应发展中的潜力.
科学领域:
- 有机化学 有机化学
- 合成化学 合成化学
- 催化剂是一种催化剂.
背景情况:
- 已知两氨基化物存在于稳定的二元体中.
- 多米诺反应通过连续执行多个转换提供了高效的合成途径.
- 控制基于分子结构的反应性在有机合成中至关重要.
研究的目的:
- 为了研究二元性两氨基化物和α,β不和化物之间的多米诺反应.
- 探索二维状态对反应结果的影响.
- 发现新的循环化途径和合成应用的两分子.
主要方法:
- 在阿扎-迈克尔/阿尔多尔多米诺反应中利用二次的两氨基化物.
- 采用反应条件,保持二分体稳定性.
- 使用分析技术来表征得到的1,5-氨基基化物.
主要成果:
- 稳定的1,5-氨基甲的高产量和二元选择性得到了实现.
- 氨基化物的二次性质对于指导反应途径至关重要.
- 通过控制二元解离,成功实现了一种新的8-诺伦多 (enolendo) -exo-trig循环.
结论:
- 两氨基化物可以有效地用于多米诺反应,从而产生有价值的产物.
- 这些分子固有的二维结构使其具有独特的反应性和立体化学控制.
- 这项研究扩大了在有机合成中使用两分子发现反应的范围.
相关概念视频
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Direct alkylation of ammonia produces polyalkylated amines, along with a quaternary ammonium salt. To exclusively prepare primary amines, the azide synthesis method can be used.
Azide ions act as good nucleophiles and react with unhindered alkyl halides to form alkyl azides. Alkyl azides do not participate in further nucleophilic substitution reactions, thereby eliminating the chances of polyalkylated products. Alkyl azides are reduced by hydride-based reducing agents, like lithium aluminum...
Azide ions act as good nucleophiles and react with unhindered alkyl halides to form alkyl azides. Alkyl azides do not participate in further nucleophilic substitution reactions, thereby eliminating the chances of polyalkylated products. Alkyl azides are reduced by hydride-based reducing agents, like lithium aluminum...
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In the presence of an aqueous base and a halogen, primary amides can lose the carbonyl (as carbon dioxide) and undergo rearrangement to form primary amines. This reaction, called the Hofmann rearrangement, can produce primary amines (aryl and alkyl) in high yields without contamination by secondary and tertiary amines.
Amines to Amides: Acylation of Amines
Various carboxylic acid derivatives (such as acid chlorides, esters, and anhydrides) can be used for the acylation of amines to yield amides. The reaction requires two equivalents of amines. The first amine molecule functions as a nucleophile and attacks the carbonyl carbon to produce a tetrahedral intermediate. This is followed by the loss of the leaving group and restoration of the C=O bond.
Next, the second equivalent of amine serves as a Brønsted base and deprotonates the quaternary amide...
Next, the second equivalent of amine serves as a Brønsted base and deprotonates the quaternary amide...
Acid Halides to Amides: Aminolysis
Aminolysis is a nucleophilic acyl substitution reaction, where ammonia or amines act as nucleophiles to give the substitution product. Acid halides react with ammonia, primary amines, and secondary amines to yield primary, secondary, and tertiary amides, respectively.
In the first step of the aminolysis mechanism, the amine attacks the carbonyl carbon of the acyl chloride to form a tetrahedral intermediate. In the second step, the carbonyl group is re-formed with the elimination of a chloride...
In the first step of the aminolysis mechanism, the amine attacks the carbonyl carbon of the acyl chloride to form a tetrahedral intermediate. In the second step, the carbonyl group is re-formed with the elimination of a chloride...
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The reaction of weakly electrophilic aryldiazonium (also called arenediazonium) salts with highly activated aromatic compounds leads to the formation of products with an —N=N— link, called an azo linkage. This reaction, presented in Figure 1, is known as diazo coupling and occurs without the loss of the nitrogen atoms of the aryldiazonium salt. Highly activated aromatic compounds such as phenols or arylamines favor the diazo coupling reaction. The coupling generally occurs at the para position.
Preparation of 1° Amines: Hofmann and Curtius Rearrangement Mechanism
The Hofmann and Curtius rearrangement reactions can be applied to synthesize primary amines from carboxylic acid derivatives such as amides and acyl azides. In the Hofmann rearrangement, a primary amide undergoes deprotonation in the presence of a base, followed by halogenation to generate an N-haloamide. A second proton abstraction produces a stabilized anionic species, which rearranges to an isocyanate intermediate via an alkyl group migration from the carbonyl carbon to the neighboring...


