亚扎-氧基离子中间体的生成和反应性:亚扎- [4 + 3] 循环添加反应用于异环合成
Christopher S Jeffrey1, Korry L Barnes, John A Eickhoff
1Department of Chemistry, University of Nevada-Reno, Reno, Nevada 89557, USA. cjeffrey@unr.edu
Journal of the American Chemical Society
|May 4, 2011
概括
这项研究详细介绍了使用由α-胺基生成的aza-oxyallylcationic中间体的aza- [4 + 3]循环添加. 该反应是分立选择性和一般适用的,N-基团增强中间稳定性.
科学领域:
- 有机化学 有机化学
- 合成化学 合成化学
- 反应机制 反应机制
背景情况:
- Aza- [4 + 3] 循环添加是有价值的合成转换.
- 需要进一步研究aza-oxyallylcationic中间体的生成和反应性.
- 了解影响中间稳定性的因素对于反应控制至关重要.
研究的目的:
- 报告使用aza-oxyallylcationic中间体的aza- [4 + 3]循环添加物的发展.
- 为了研究与各种α-胺胺的反应的范围和 diastereoselectivity.
- 探索N-alkoxy替代剂对aza-oxyallylcationic中间体的稳定作用.
主要方法:
- α-胺酸的脱化,以产生aza-oxyallylcationic中间体.
- 循环添加反应与循环二烯.
- 灾难选择性分析.
- 计算建模和实验验证.
主要成果:
- 成功实施了一系列α-胺基的aza- [4 + 3]循环添加.
- 在循环加法过程中表现出良好的二聚体选择性.
- 鉴定N-基替代剂作为aza-oxyallylcationic中间体的关键稳定组.
- 通过计算和实验数据确认反应机制.
结论:
- α-胺衍生物中间体的aza- [4 + 3] 循环添加是高效的,并且具有异构选择性.
- N-alkoxy替代显著稳定了关键的阴离子中间体,促进了反应.
- 这种方法为构建含有的复杂异环化合物提供了一条通用的途径.
相关概念视频
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.
Cycloaddition Reactions: MO Requirements for Thermal Activation
Thermal cycloadditions are reactions where the source of activation energy needed to initiate the reaction is provided in the form of heat. A typical example of a thermally-allowed cycloaddition is the Diels–Alder reaction, which is a [4 + 2] cycloaddition. In contrast, a [2 + 2] cycloaddition is thermally forbidden.
Aryldiazonium Salts to Azo Dyes: Diazo Coupling
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.
Cycloaddition Reactions: MO Requirements for Photochemical Activation
Some cycloaddition reactions are activated by heat, while others are initiated by light. For example, a [2 + 2] cycloaddition between two ethylene molecules occurs only in the presence of light. It is photochemically allowed but thermally forbidden.
Pericyclic Reactions: Introduction
Pericyclic reactions are organic reactions that occur via a concerted mechanism without generating any intermediates. The reactions proceed through the movement of electrons in a closed loop to form a cyclic transition state, where rearrangement of the σ and π bonds yields specific products.
Pericyclic reactions can be classified into three categories: electrocyclic reactions, cycloaddition reactions, and sigmatropic rearrangements. Electrocyclic reactions and sigmatropic rearrangements are...
Pericyclic reactions can be classified into three categories: electrocyclic reactions, cycloaddition reactions, and sigmatropic rearrangements. Electrocyclic reactions and sigmatropic rearrangements are...
Preparation of 1° Amines: Azide Synthesis
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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