活性化されていないアミドの触媒性シリコン媒介の炭素-炭素結合形成反応
Shū Kobayashi1, Hiroshi Kiyohara, Miyuki Yamaguchi
1Department of Chemistry, School of Science, University of Tokyo, and The HFRE Division, ERATO, Japan Science Technology Agency, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. shu_kobayashi@chem.s.u-tokyo.ac.jp
Journal of the American Chemical Society
|December 22, 2010
まとめ
この研究では,活性化されていないアミドとイミンを用いてマニッヒ型アダクトを合成するための新しい触媒方法が紹介されています. この画期的な発見により,効率的な直接型添加反応が可能になり,有機化学における合成の可能性が拡大しました.
科学分野:
- 有機化学 オーガニック・ケミストリー
- カタリシス カタリシス カタリシス
- 合成方法論 合成方法論
背景:
- シリコンエノラートは,有機合成における確立された反応剤である.
- アミドを含む直接的な触媒添加反応は,それほど一般的ではありません.
- 非活性化アミドは,機能化のために通常より厳しい条件を必要とします.
研究 の 目的:
- イミンに非活性化アミドを直接添加するための触媒的方法の開発.
- マニッヒ型アダクト形成において,高収量とステレオ選択性を達成するために.
- アミド機能化におけるシリコン種の触媒的有用性を調査する.
主な方法:
- 活性化されていないアミドとイミンの反応.
- トライアキルシリルトリフラートとトライエチラミンの触媒用量を使用します.
- 現場で生成されたシリコンエノラートを使用しています.
主要な成果:
- マニッヒ型アダクトの高収量と高反選択性が達成されました.
- この変換のためのシリコン種の最初の触媒的使用を実証した.
- 直接添加で,より酸性少ないアルファ陽子を持つアミドを成功裏に採用した.
結論:
- 活性化されていないアミドを用いた新しい,効率的な触媒マニッヒ反応が開発されました.
- この方法は,触媒的な直接型添加反応における重要な進歩を表しています.
- 予備的な非対称な触媒試験は,エナチオセレクティブ合成の可能性を示しています.
関連する概念動画
01:29Preparation 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...
01:28Amides to Carboxylic Acids: Hydrolysis
Amides can undergo either acid-catalyzed hydrolysis or base-promoted hydrolysis through a typical nucleophilic acyl substitution. Each hydrolysis requires severe conditions.
Acid-catalyzed hydrolysis:
Hydrolysis of amides under acidic conditions yields carboxylic acids. Since the reaction occurs slowly, hydrolysis requires the conditions of heat.
The mechanism begins with the protonation of the carbonyl oxygen by the acid catalyst. The protonation makes the amide carbonyl carbon more...
Acid-catalyzed hydrolysis:
Hydrolysis of amides under acidic conditions yields carboxylic acids. Since the reaction occurs slowly, hydrolysis requires the conditions of heat.
The mechanism begins with the protonation of the carbonyl oxygen by the acid catalyst. The protonation makes the amide carbonyl carbon more...
01:26Preparation of 1° Amines: Hofmann and Curtius Rearrangement Mechanism
The Hofmann and Curtius rearrangement reactions can be applied to synthesize primary amines from carboxylic acid derivatives such as amides and acyl azides. In the Hofmann rearrangement, a primary amide undergoes deprotonation in the presence of a base, followed by halogenation to generate an N-haloamide. A second proton abstraction produces a stabilized anionic species, which rearranges to an isocyanate intermediate via an alkyl group migration from the carbonyl carbon to the neighboring...
01:19Amines 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...
01:16Aldehydes 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.
02:27Preparation 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.