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主要氨基酸和次要胺酸之间的TiIV介导反应:氨基酸形成与转氨基化相比
Denis A Kissounko1, Justin M Hoerter, Ilia A Guzei
1Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA.
Journal of the American Chemical Society
|February 8, 2007
概括
(IV) 复合物介于氨基和碳胺之间的反应,产生胺或转化产物. 特定的 (IV) 复合物和反应条件决定了结果,催化 (NMe2) 4有利于选择性转米化.
科学领域:
- 有机金属化学 有机金属化学
- 催化剂是一种催化剂.
- 有机合成 有机合成
背景情况:
- 众所周知, (IV) 复合物能够调解涉及氨基和胺的反应.
- 这些反应的结果,特别是胺形成与转化,对特定的复合物和反应条件敏感.
- 了解控制这种选择性的因素对于开发高效的催化过程至关重要.
研究的目的:
- 调查原始氨基和二次碳胺胺之间的中介反应中不同结果的机械起源.
- 阐明不同 (IV) 复合物和反应条件在控制选择性的作用.
- 为了确定有利于选择性转米化而不是氨基胺形成的条件.
主要方法:
- 使用Cp*TiIV复合体和Ti(NMe2)4.4的固体测量反应
- 在不同的条件下使用不同的 (IV) 复合物 (Cp * TiIV 和 Ti (NMe2) 4) 的催化反应.
- 对反应产物的分析,以确定对胺素形成或转胺的选择性.
主要成果:
- 立体测量 (IV) 促进了阿米丁和氧产品的形成.
- 催化性Cp*TiIV复合物导致竞争性氨基胺的形成和转氨基胺转化,通常有利于氨基胺.
- 催化剂Ti(NMe2) 4 (≤20 mol %) 选择性地促进了转化,避免了氧化的形成.
结论:
- (IV) 复合物的身份对于确定氨基-碳胺合反应的结果至关重要.
- 催化Ti(NMe2) 4提供了一种高度选择性的转化途径,克服了与氧副产品形成相关的局限性.
- 这些发现对有机合成中 (IV) 催化剂的设计和应用有重大影响.
相关概念视频
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...
Preparation of Amides
Amides are synthesized by treating carboxylic acids with amines in the presence of dehydrating agents like dicyclohexylcarbodiimide (DCC).
The DCC-promoted synthesis of amides begins with the protonation of DCC by carboxylic acid. The protonation makes it a better acceptor. Next, the addition of carboxylate to the protonated carbodiimide gives a reactive acylating agent.
Subsequently, the amine acts as a nucleophile that attacks the acylating agent to form a tetrahedral intermediate. In the...
The DCC-promoted synthesis of amides begins with the protonation of DCC by carboxylic acid. The protonation makes it a better acceptor. Next, the addition of carboxylate to the protonated carbodiimide gives a reactive acylating agent.
Subsequently, the amine acts as a nucleophile that attacks the acylating agent to form a tetrahedral intermediate. In the...
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.
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 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...

