末端アルキネへのアルデヒドのルテニウム触媒によるデカルボニラティブ添加によるオレフィネーション
Xiangyu Guo1, Jun Wang, Chao-Jun Li
1Department of Chemistry, McGill University, Montreal, QC, Canada H3A 2K6.
Journal of the American Chemical Society
|November 19, 2009
まとめ
ルテニウム触媒は,アルデヒドとアルキンを効率的に結合させ,新しいデカルボニラティブオレフィネーション反応を可能にします. この方法は,アロマティックアルデヒドとアリファティックアルデヒドを区別して,高い化学選択性を示しています.
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
- 有機金属化学 有機金属化学
背景:
- オレフィネーション反応は,有機合成におけるC−C結合形成に不可欠である.
- オレフィネーションのための選択的で効率的な触媒方法の開発は,依然として研究活動の活発な分野です.
- 脱炭素化反応は,容易に入手可能なカルボニル化合物を利用することによって,原子経済性を提供します.
研究 の 目的:
- 新しいルテニウム触媒によるオレフィネーション反応の開発.
- アルデヒドとアルキンのデカルボニラティブ添加を調査する.
- 異なるアルデヒド型との反応の化学選択性を探求する.
主な方法:
- ルテニウム触媒反応の最適化について.
- アロマティック・アルデヒドおよびアリファティック・アルデヒドを含む基質の範囲調査.
- 電子効果と選択性を理解するためのメカニズム研究.
主要な成果:
- アルデヒドとアルキンのルテニウム触媒によるデカルボニラティブオレフィネーションの成功開発.
- 反応経路に影響を与える強力な電子効果の観測.
- アロマティックアルデヒドとアリファティックアルデヒドの間の高い化学選択性の実証.
結論:
- 開発されたルテニウム触媒は,デカルボニラティブ添加によるオレフィネーションの効率的な経路を提供します.
- 反応は,有意な電子制御を示し,選択的な機能化を可能にします.
- この方法論は,複雑な有機分子を構築するための貴重なツールを提供します.
関連する概念動画
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.
02:04Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
Diols are compounds with two hydroxyl groups. In addition to syn dihydroxylation, diols can also be synthesized through the process of anti dihydroxylation. The process involves treating an alkene with a peroxycarboxylic acid to form an epoxide. Epoxides are highly strained three-membered rings with oxygen and two carbons occupying the corners of an equilateral triangle. This step is followed by ring-opening of the epoxide in the presence of an aqueous acid to give a trans diol.
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.
01:17Radical Anti-Markovnikov Addition to Alkenes: Mechanism
The reaction of hydrogen bromide with alkenes in the presence of hydroperoxides or peroxides proceeds via anti-Markovnikov addition. The radical chain reaction comprises initiation, propagation, and termination steps.
The mechanism starts with chain initiation, which involves two steps. In the first chain initiation step, a weak peroxide bond is homolytically cleaved upon mild heating to form two alkoxy radicals. In the second initiation step, a hydrogen atom is abstracted by the alkoxy radical...
The mechanism starts with chain initiation, which involves two steps. In the first chain initiation step, a weak peroxide bond is homolytically cleaved upon mild heating to form two alkoxy radicals. In the second initiation step, a hydrogen atom is abstracted by the alkoxy radical...
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.