イミンの触媒的非対称性アンポルング反応
Yongwei Wu1, Lin Hu1, Zhe Li1
1Department of Chemistry, Brandeis University, 415 South Street, Waltham, Massachusetts 02454, USA.
Nature
|July 24, 2015
まとめ
研究者は,イミンの非対称的なアンポルング反応のための新しいキラル相移転触媒を開発した. この突破によりイミンは核愛素として機能し,キラルアミンを効率的かつ選択的に合成するための新しい経路を生み出します.
科学分野:
- 有機化学
- 非対称な触媒
背景:
- イミンは有機合成において極めて重要であり,通常,炭素-炭素結合を形成し,アミンを合成するために電愛素として作用する.
- イミンの電子的性質を逆転させ 核愛者として振る舞うことで 新しい合成戦略が解き放たれます
- イミンの非対称性アンポルング反応は,その潜在的影響にもかかわらず,未発達である.
研究 の 目的:
- イミンの非対称的なアンポルング反応のための新しいキラル相移転触媒の発見と開発.
- イミンが炭素電化分子との反応で核愛素として機能できるようにする.
- キラルアミンを合成するための新しい,効率的で選択的な方法を確立する.
主な方法:
- 新しいキラル・フェーズ・トランスファー・カタリストの開発
- これらの触媒を用いてイミンの脱プロトン化を行い,2-アザリルアニオンを形成する.
- これらのアニオンの反応をエナル (炭素電ophiles) と指示する.
主要な成果:
- イミンとエナルの高効率な非対称性アンポルング反応を達成した.
- 触媒は高い化学選択性,地域選択性,二重選択性,およびエナチオ選択性を示した.
- 反応は高収量で,様々な基板を許容し,最小の触媒負荷 (0.01%mol) を要求する.
- 湿気と空気を耐える 動作プロトコルを開発した.
結論:
- imine umpolungを用いた非対称合成に対する概念的に新しいアプローチを導入した.
- キラルアミノ化合物を合成するための実用的で効率的な方法を提供した.
- 開発された触媒と方法論は,非対称合成の新たな道を開きます.
関連する概念動画
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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.
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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...
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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...
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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...
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