アルキネスのヘテロアトム誘導アルキルシアン化
Yoshiaki Nakao1, Akira Yada, Tamejiro Hiyama
1Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan. yoshiakinakao@npc05.mbox.media.kyoto-u.ac.jp
Journal of the American Chemical Society
|July 3, 2010
まとめ
ニッケル/ルイス酸触媒により,ガンマ・ヘテロ原子で置換されたアルカネニトリルは,アルキン全体にステレオおよび地域選択的に添加することができる. この反応により,高度に置換されたアクリロニトリルが生み出され,新しい合成経路が示されます.
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:
- ガンマヘテロ原子を持つアルカネニトリルは,貴重な合成前駆体である.
- ステレオおよび地域選択的加法反応は,複雑な分子合成において極めて重要です.
- ニッケル触媒反応は,有機合成においてユニークな反応パターンを提供します.
研究 の 目的:
- 高度に置換されたアクリロニトリルを合成するための新しい方法を開発する.
- ガンマ・ヘテロ原子で置換されたアルカネニトリルのアルキネへのステレオおよび地域選択的添加を調査する.
- ニッケルとルイス酸を含む触媒メカニズムを解明する.
主な方法:
- 添加反応にはニッケル/ルイス酸触媒を用いた.
- 基質として,ガンマ・ヘテロ原子で置換されたアルカネニトリルとアルキンを用いる.
- ステレオ化学と地域化学のために反応製品を分析する.
主要な成果:
- アルカニニトリルのステレオおよび地域選択的添加をアルキネス全体で達成した.
- 一連の高度に置換されたアクリロニトリルを合成することに成功しました.
- 触媒サイクルにおけるヘテロ原子協調の重要な役割を実証した.
結論:
- ニッケル/ルイス酸触媒は,代用されたアクリロニトリルへの効率的な経路を提供します.
- 5基のニッケルサイクルの中間物質を含む提案されたメカニズムは,観察された選択性を説明します.
- この方法論は,有機化学におけるアルカネニトリルの合成的有用性を拡大する.
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.
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.
02:40Alkynes to Aldehydes and Ketones: Acid-Catalyzed Hydration
Introduction
Analogous to alkenes, alkynes also undergo acid-catalyzed hydration. While the addition of water to an alkene gives an alcohol, hydration of alkynes produces different products such as aldehydes and ketones.
Analogous to alkenes, alkynes also undergo acid-catalyzed hydration. While the addition of water to an alkene gives an alcohol, hydration of alkynes produces different products such as aldehydes and ketones.
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.
02:34Preparation of Alkynes: Dehydrohalogenation
Introduction
Alkynes can be prepared by dehydrohalogenation of vicinal or geminal dihalides in the presence of a strong base like sodium amide in liquid ammonia. The reaction proceeds with the loss of two equivalents of hydrogen halide (HX) via two successive E2 elimination reactions.
Alkynes can be prepared by dehydrohalogenation of vicinal or geminal dihalides in the presence of a strong base like sodium amide in liquid ammonia. The reaction proceeds with the loss of two equivalents of hydrogen halide (HX) via two successive E2 elimination reactions.