帕拉催化了芳香C-H键与氧胺 Ester 的氨基化
1Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA.
Journal of the American Chemical Society
|March 2, 2010
概括
研究人员开发了一种新的方法,用于使用氧基的直接芳香C-H键氨基化. 这种催化反应在温和条件下形成产物,提供了一种新的合成途径.
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:
- 直接的C-H键功能化是合成化学的一个关键领域.
- 为芳香C-H氨基化开发高效和选择性的方法仍然是一个挑战.
- 的催化提供了C-H激活和功能化的多功能途径.
研究的目的:
- 引入一种新的,概念上的新方法,用于直接氨基化芳香C-H键.
- 探索氧化以氧化中性条件下与芳香C-H键的反应.
- 为了研究涉及类物种的催化机制.
主要方法:
- 使用氧化埃斯特作为氨基化剂.
- 使用低负荷 (1mol%) 的催化剂.
- 在氧化还原中性条件下进行反应.
- 隔离和表征中间的复合物.
主要成果:
- 成功地实现了芳香C-H键的直接氨基化.
- 印产品是由氧化与芳香C-H键的反应形成的.
- 催化过程在低催化剂负载下运行.
- 提出了一个不寻常的初始氧化添加N-O键到Pd(0) 物种.
- 由N-X键的氧化添加而产生的Pd(II) 复合物首次被分离出来.
结论:
- 已经建立了一种新的,高效的直接芳香C-H氨化方法.
- 反应通过一种涉及初始N-O键氧化添加到的拟议机制进行.
- 关键的中间体的分离为拟议的催化循环提供了证据.
相关概念视频
Preparation of Amines: Reduction of Oximes and Nitro Compounds
Oximes can be reduced to primary amines using catalytic hydrogenation, hydride reduction, or sodium metal reduction. The reduction of aliphatic and aromatic nitro compounds to primary amines takes place by either catalytic hydrogenation or by using active metals like Fe, Zn, and Sn in the presence of an acid.
Though catalytic hydrogenation can reduce nitrobenzenes, the reduction is nonselective in the presence of other functional groups. For instance, if nitrobenzene contains an aldehyde group,...
Though catalytic hydrogenation can reduce nitrobenzenes, the reduction is nonselective in the presence of other functional groups. For instance, if nitrobenzene contains an aldehyde group,...
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...
Amines to Alkenes: Hofmann Elimination
Alkenes can be obtained from amines via an E2 elimination. The amine is first converted into a good leaving group, such as a quaternary ammonium salt. This is accomplished by treating the amine with an excess of alkyl halide, which results in a halide salt. Next, the halide salt is transformed into a hydroxide salt that functions as a base to enable elimination.
Under thermal conditions, the hydroxide can abstract a proton from the β carbon; this generates an alkene with the simultaneous...
Under thermal conditions, the hydroxide can abstract a proton from the β carbon; this generates an alkene with the simultaneous...
Amines to Alkenes: Cope Elimination
Cope elimination reaction involves the conversion of tertiary amines to alkene using hydrogen peroxide under thermal conditions, as depicted in figure 1.
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...
Preparation of Amines: Reductive Amination of Aldehydes and Ketones
Carbonyl compounds and primary amines undergo reductive amination first to produce imines, followed by secondary amines in the same reaction mixture, using selective reducing agents like sodium cyanoborohydride or sodium triacetoxyborohydride. Reductive amination produces different degrees of substitution of amines depending on the starting amine substrate.


