アルファシリルケトンから派生したアルキリデンカルベンのサイクロプロペネーション
Jingwei Li1, Chunrui Sun, Daesung Lee
1Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607-7061, USA.
Journal of the American Chemical Society
|April 24, 2010
まとめ
研究者らは,アルキリデンカルベンを用いた新しいサイクロプロパネーション反応を開発した. この方法は,選択的に炭素-シリコン結合に挿入し,有機化学における新しい合成経路を提供します.
科学分野:
- 有機化学 オーガニック・ケミストリー
- オーガノシリコン化学 化学
- 合成方法論 合成方法論
背景:
- サイクロプロパネーション反応は,有機合成において根本的な役割を果たします.
- アルキリデンカルベンは,多用途の中間物質である.
- カーベンの挿入反応における選択性を制御することは,依然として課題です.
研究 の 目的:
- 新しいサイクロプロパネーション反応を開発するために.
- アルファシリルケトンから派生したアルキリデンカーベンの反応性を調査する.
- カーベンの挿入選択性を支配する要因を理解する.
主な方法:
- アルファシリルケトンからアルキリデンカルベンの生成.
- カーベンの基板との反応により,サイクロプロパンが形成されます.
- 選択性を決定するために反応産物の分析.
主要な成果:
- Calpha-Si結合の挿入を含む新しいサイクロプロパネーション反応が開発されました.
- この反応は,Cgamma-Hの挿入または不飽和結合の添加よりも,Calpha-Si結合の挿入に優れた選択性を示した.
- Tetherのアルファ酸素はCgamma-H挿入を促進することが判明したが,Calpha-Si挿入は競争力があった.
結論:
- 開発されたサイクロプロパネーション反応は,カルファ-Si結合挿入によるサイクロプロパネの形成のための新しい経路を提供します.
- この研究は,アルファシリルケトン由来カルベンのユニークな反応性を強調しています.
- 選択性因子の理解は,将来の合成戦略を設計するための洞察を提供します.
関連する概念動画
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.
02:24Reduction 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.
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01:16[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
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.
01:22Alkenes via Reductive Coupling of Aldehydes or Ketones: McMurry Reaction
The radical dimerization of ketones or aldehydes gives vicinal diols through a pinacol coupling reaction. However, the behavior of titanium metals used for the reaction as a source of electrons is unusual. When the reaction is carried out in the presence of titanium, diols can be isolated at low temperatures. Else titanium further reacts with diols, forming alkenes through the McMurry reaction.
01:28Diels–Alder Reaction Forming Cyclic Products: Stereochemistry
The Diels–Alder reaction is one of the robust methods for synthesizing unsaturated six-membered rings. The reaction involves a concerted cyclic movement of six π electrons: four π electrons from the diene and two π electrons from the dienophile.