グループ制御された水酸化を誘導:アルキネの地域選択的機能化
Yuuya Kawasaki1, Youhei Ishikawa, Kazunobu Igawa
1Department of Molecular and Material Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Japan.
Journal of the American Chemical Society
|December 7, 2011
まとめ
ディメチルビニルシリル (DMVS) 誘導基を用いたプラチナ触媒化水酸化は,非対称アルキンの高い地域選択性を達成する. この方法により,特定のシライラルケンの同位体および多様な機能化された化合物の合成が可能になります.
科学分野:
- 有機金属化学 有機金属化学
- 合成有機化学 合成有機化学について
- カタリシス カタリシス カタリシス
背景:
- 水塩酸化は有機合成の重要な反応である.
- アルキンの水溶化における地域選択性を制御することは,依然として課題です.
- グループを指揮することで,反応の結果に影響を与えることができます.
研究 の 目的:
- 非対称アルキンの高度に地域選択性のあるPt(0) -触媒化水酸化を開発する.
- ダイメチルビニルシリル (DMVS) 群が指向・加速群としての役割を調査する.
- 非対称アルキンから複合アルケーンと機能化された化合物の合成を探求する.
主な方法:
- プラチナ (((0) -触媒化水酸化反応.
- ディメチルビニルシリル (DMVS) を非対称アルキンの指向群として利用.
- 結果となるシリアルケネンの後の変換反応.
主要な成果:
- 非対称性アルキンの水酸化で高い地域選択性を達成した.
- DMVSグループは,シリアルケンの単一のレジオアイソメルの形成を指揮しました.
- DMVS群の選択的水溶化に対する加速度効果が観察されました.
- 様々な三置換アルケーンと,高地域選択性を持つ多酸化機能化化合物を合成した.
結論:
- DMVSグループは,Pt(0) -触媒化されたアルキンの水酸化を効率的に誘導し,加速するグループです.
- この方法論は,価値あるアルケンの誘導体への地域選択的な経路を提供します.
- 単純なアルキンから複雑な有機分子の効率的な合成を可能にします.
関連する概念動画
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.
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.
02:34Regioselectivity 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.
02:36Regioselectivity and Stereochemistry of Hydroboration
A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
02:17Regioselectivity 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...
02:35Electrophilic Addition to Alkynes: Hydrohalogenation
Electrophilic addition of hydrogen halides, HX (X = Cl, Br or I) to alkenes forms alkyl halides as per Markovnikov's rule, where the hydrogen gets added to the less substituted carbon of the double bond. Hydrohalogenation of alkynes takes place in a similar manner, with the first addition of HX forming a vinyl halide and the second giving a geminal dihalide.