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プライマリアミンと二次カルボキシアミドの間のTiIV媒介反応:アミジン形成とトランスアミデーションの比較
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
まとめ
タイタニウム (IV) 複合体は,アミンとカルボキシアミドの間の反応を媒介し,アミジンまたはトランスアミデーション製品を生成します. 特定のチタン (((IV)) 複合体と反応条件が結果を決定し,触媒Ti (((NMe2) 4が選択的トランスアミデーションを好む.
科学分野:
- 有機金属化学 有機金属化学
- カタリシス カタリシス カタリシス
- オーガニック・シンセシス オーガニック・シンセシス
背景:
- タイタニウム (IV) 複合体は,アミンとアミドを含む反応を媒介することが知られている.
- これらの反応の結果,特にアミジンの形成とトランスアミジンの形成は,特定のチタン複合体と反応条件に敏感です.
- この選択性を制御する要因を理解することは,効率的な触媒プロセスの開発に不可欠です.
研究 の 目的:
- 主要アミンと二次カルボキシアミドのチタニウム ((IV)) 媒介反応における異なった結果のメカニズム的起源を調査する.
- 選択性を制御する際の異なるチタン (((IV)) 複合体と反応条件の役割を明らかにする.
- アミジン形成よりも選択的トランスアミデーションを好む条件を特定する.
主な方法:
- Cp*TiIV複合体とTi(NMe2) を用いたステキオメトリック反応4.4.
- 異なる条件下で,異なるチタン (((IV) 複合体 (Cp*TiIVとTi (((NMe2)4) を使った触媒反応.
- アミジンの形成またはトランスアミジンの選択性を決定するための反応産物の分析.
主要な成果:
- ステイキオメトリックチタン ((IV)) は,アミジンとオクソチタニウム製品形成を促進します.
- 触媒性Cp*TiIV複合体は,競争的なアミジン形成とトランスアミダイゼーションにつながり,一般的にアミジンを好みます.
- 触媒Ti(NMe2)4 (≤20mol %) は選択的にトランスアミデーションを促進し,オキシトチタニウム形成を回避する.
結論:
- タイタン (((IV) 複合体のアイデンティティは,アミン-カルボキシアミド結合反応の結果を決定する上で極めて重要です.
- 触媒Ti ((NMe2) 4) は,トランスアミド化への高度な選択的経路を提供し,オキシトチタニウム副産物形成に関連する制限を克服します.
- これらの発見は,有機合成におけるチタン (IV) 触媒の設計と応用に重大な意味を持つ.
関連する概念動画
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...

