アルキノンのオルガノカタリティック・エナチオセレクティブ・コンジュガット添加
Marco Bella1, Karl Anker Jørgensen
1Danish National Research Foundation: Center for Catalysis, Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark.
Journal of the American Chemical Society
|May 6, 2004
まとめ
この研究は,アルキノンにベータ-ディカルボニル化合物の最初のエナチオセレクティブ触媒添加を導入します. 開発された有機触媒法では,キラルエノンの製品に対して,高い収穫量と優れたエナチオ選択性を得ています.
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
- アシンメトリック・シンセシス
背景:
- ベータ-ジカルボニル化合物は,汎用性の高い合成ビルディングブロックです.
- アルキノンは,有機合成における貴重なマイケル受容体である.
- 結合添加のためのエナンチオセレクティブの方法の開発は,キラル分子の合成に不可欠です.
研究 の 目的:
- アルキノンにベータ-ディカルボニル化合物の最初の触媒的エナチオセレクティブ結合添加を提示する.
- 光学的に活発な (E) -enoneアドクトにアクセスするための効率的なワンポット手順を開発する.
主な方法:
- シンコナアルカロイド [DHQ]2PHALを有機触媒として利用した.
- [DHQ]2PHALとトリブチルフォスフィン (Bu3P) を含む2段階,1ポット触媒システムを採用しました.
- ベータ・ディカルボニル化合物とアルキノンの間の結合添加反応を調査した.
主要な成果:
- 結合添加反応で非常に高い収量を得ました.
- (Z) -および (E) -エノンの混合物で,最大95%のエナティオメール過量 (ee) が得られました.
- 光学的に活性な (E) -enoneアダクトを生成するワンポット手順を成功裏に開発しました.
結論:
- 開発された有機触媒法は,非対称合成における重要な進歩を表しています.
- ワンポット手順は,エナチオメリックに濃縮された (E) -エノンのための効率的な経路を提供します.
- この方法論は,複雑なキラル分子の合成のための強力なツールを提供します.
さらに関連する動画
関連する概念動画
02:24Introduction to Electrophilic Addition Reactions of Alkenes
The double bond in a simple, unconjugated alkene is a region of high electron density that can act as a weak base or a nucleophile. The filled π orbital (HOMO) of the double bond can interact with the empty LUMO of an electrophile. A bonding interaction occurs when the electrophile attacks between the two carbons; the electrophile then accepts a pair of electrons from the π bond and undergoes addition across the double bond, yielding a single product.
Addition and elimination reactions can be...
Addition and elimination reactions can be...
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.
02:38Electrophilic Addition to Alkynes: Halogenation
Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
Introduction
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
01:09Conjugate Addition to α,β-Unsaturated Carbonyl Compounds
α,β-Unsaturated carbonyl compounds are molecules bearing a carbonyl and alkene functionality in conjugation with each other. The conjugation in the molecule leads to three resonance structures. The hybrid form exhibits two probable electrophilic sites: the carbonyl carbon and the β carbon.