機能化されたアルケンのステレオ選択的分子間アリルC-Hトリフルオロアセトキシル化
Rauful Alam1, Lukasz T Pilarski, Elias Pershagen
1Department of Organic Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden.
Journal of the American Chemical Society
|May 17, 2012
まとめ
この研究では,新しい酸化物質を用いたアルケンのトリフオロアセトキシル化のためのパラジウム触媒法が導入されています. この反応は,周期性アルケンの高レジオおよびダイアステレオ選択性を示し,新しい合成経路を提供した.
科学分野:
- 有機化学 オーガニック・ケミストリー
- 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
背景:
- アリルC-H機能化は,有機合成における重要な変換である.
- パラジウム触媒は,C-H活性化と機能化のための多用途な経路を提供します.
- アリル基の位置に酸素化された機能を導入するための選択的方法の開発は,依然として研究の活発な分野です.
研究 の 目的:
- 代替アルケンの直接C-H三酸塩酸化のための新しいパラジウム触媒法を開発する.
- サイクルアルケーンにおけるこの変換の地域およびダイアステレオ選択性を調査する.
- パラジウム中間物質の役割を含む反応機構の解明.
主な方法:
- パラジウム触媒反応は,PhI ((OCOCF3) 2) を酸化剤とアシロキシ源の両方として利用しています.
- 各種置換アルケーンを用いた基質の範囲調査,単位置換サイクロペンテンとサイクロヘキセンに焦点を当てた.
- 潜在的 (η3-アルリル) Pd (II) 中間物質の特徴と反応性を含むメカニズム研究.
主要な成果:
- 代替アルケンのPd触媒によるアリルC-Hトリフルオロアセトキシル化が成功しました.
- 単位置換サイクロペンテンとサイクロヘクセンのトリフッロアセトキシル化において,優れた地域およびダイアステロ選択性が観察されました.
- 機械学的調査は,ステレオセレクティブのPd (IV) 中間物質と,その後の還元性排除の関与を示唆しています.
結論:
- パラジアム触媒によるアリルC-Hトリフルオロアセトキシル化の新しく効率的な方法が確立されました.
- この反応は,トリフロアセトキシル化サイクルアルケーンへの高度な選択的経路を提供します.
- Pd(IV) 中間物質を含む提案されたメカニズムは,反応の立体化学的制御の洞察を提供します.
さらに関連する動画
関連する概念動画
Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
If a set of reactants can yield multiple constitutional isomers, but one of the isomers is obtained as the major product, the reaction is said to be regioselective. In such reactions, bond formation or breaking is favored at one reaction site over others.
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
Acid-Catalyzed α-Halogenation of Aldehydes and Ketones
By replacing an α-hydrogen with a halogen, acid-catalyzed α-halogenation of aldehydes or ketones yields a monohalogenated product
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
Reduction 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.
Preparation 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.
Electrophilic Aromatic Substitution: Friedel–Crafts Acylation of Benzene
The Friedel–Crafts acylation reactions involve the addition of an acyl group to an aromatic ring. These reactions proceed via electrophilic aromatic substitution by employing an acyl chloride and a Lewis acid catalyst such as aluminum chloride to form aryl ketone.
Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
The rate of acid-catalyzed hydration of alkenes depends on the alkene's structure, as the presence of alkyl substituents at the double bond can significantly influence the rate.


