11组金属胺催化不对称的环添加反应中,亚甲胺因与终端基因的反应发生
Takaki Imaizumi1, Yasuhiro Yamashita, Shū Kobayashi
1Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Journal of the American Chemical Society
|December 1, 2012
概括
我们开发了一种新型的催化方法,用11组金属胺基合成N,N-双循环pyrazolidinone衍生物. 这种反应在不对称合成中提供了高产量,区域选择性和酶选择性.
科学领域:
- 有机化学 有机化学
- 催化剂是一种催化剂.
- 异环化学 异环化学
背景情况:
- 1,3-双极循环添加反应对于构建异环化合物至关重要.
- 为这些反应开发高效的催化系统仍然是活跃的研究领域.
- 亚甲胺胺和终端基是有机合成中的多功能构建块.
研究的目的:
- 开发一种新型的催化系统,用于1,3-双极循环添加阿佐米胺与终端基因的1,3-双极循环添加.
- 为了合成具有独特替代模式的N,N-双循环pyrazolidinone衍生物.
- 为了实现这些异环环的不对称合成,具有高的enantioselectivity.
主要方法:
- 利用11组金属胺作为循环添加反应的催化剂.
- 作为反应基质,采用了亚甲胺和终端.
- 进行了机理学研究,以了解反应途径和选择性决定因素.
主要成果:
- 通过1,3-双极循环添加成功合成了N,N-双循环pyrazolidinone衍生物.
- 在循环载荷管道中实现了独特的5.7次失置模式.
- 在不对称变异中证明了高产量,独特的区域选择性和高反选择性.
结论:
- 11组金属胺催化提供了一个有效的N,N-双循环pyrazolidinones的途径.
- 开发的方法适用于不对称的合成,产生质丰富的异环环.
- 机械洞察力揭示了在这种转型中支配区域选择性的关键因素.
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...
Aldehydes and Ketones with Amines: Imine Formation Mechanism
Imine formation involves the addition of carbonyl compounds to a primary amine. It begins with the generation of carbinolamine through a series of steps involving an initial nucleophilic attack and then several proton transfer reactions. The second part includes the elimination of water, as a leaving group, to give the imine.
Imines are formed under mildly acidic conditions. A pH of 4.5 is ideal for the reaction.
If the pH is low or the solution is too acidic, the reaction slows down in the...
Imines are formed under mildly acidic conditions. A pH of 4.5 is ideal for the reaction.
If the pH is low or the solution is too acidic, the reaction slows down in the...
Aldehydes and Ketones with Amines: Imine and Enamine Formation Overview
Primary amines react with carbonyl compounds—aldehydes and ketones—to generate imines. Imines consist of a C=N double bond and are named Schiff bases after its discoverer—the German chemist Hugo Schiff. On the other hand, secondary amines react with carbonyl compounds to give enamines. In enamines, the presence of a C=C double bond adjacent to the nitrogen atom leads to the delocalization of the lone pair.
Preparation of Alkynes: Alkylation Reaction
Introduction
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
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...
Preparation of 1° Amines: Hofmann and Curtius Rearrangement Overview
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.


