アルキンのニッケル触媒カルボシアン化により,アリルシアン化物によるカルボシアン化が行われます
Yasuhiro Hirata1, Tomoya Yukawa, Natsuko Kashihara
1Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan.
Journal of the American Chemical Society
|September 3, 2009
まとめ
アルキンのニッケル触媒によるアルリルシアネーションにより,代替ヘクサジエネニトリルが得られます. この反応は,ルイス酸によって強化され,アルコールやアミンのさらなる機能化を可能にし,天然製品の合成に適用されています.
科学分野:
- 有機金属化学 有機金属化学
- オーガニック・シンセシス オーガニック・シンセシス
- カタリシス カタリシス カタリシス
背景:
- アリルシアン酸は,多用途の合成前駆体である.
- アルキンは有機化学の基本的な構成要素である.
- 炭素-炭素結合形成の効率的な方法は,複雑な分子合成に不可欠です.
研究 の 目的:
- アリルシアン酸をアルキン酸に添加するためのニッケル触媒法を開発する.
- 開発されたアリルシアン化反応の範囲と限界を調査する.
- 機能化された分子と自然産物の合成における反応の有用性を実証する.
主な方法:
- アリルシアン化物のニッケル触媒反応により,様々なアルキンが反応する.
- ルイス酸コカタライスト (AlMe2ClまたはAlMe3) の使用は,反応性と基質の範囲を向上させる.
- 結果となる2,5-ヘクサジネンニトリルの機能群変換.
- プラウノトールの合成に対するカルボシアン化反応の適用.
主要な成果:
- ポリ置換された2,5-ヘクサジエネニトリルは,高いステレオおよび地域選択性で合成されました.
- ルイス酸コカタライストは反応を大幅に加速し,基板の互換性を拡大しました.
- シアノ基は,ヒドロキシメチルまたはアミノメチル基に成功裏に変換されました.
- アルファ-シロキシアルリルシアン酸は,3オキシプロピル機能の導入を可能にしました.
- カーボシアン化反応は,プラウノトールにおける重要な二重結合のステレオ選択的構成に適用された.
結論:
- ニッケル/フォスフィン触媒は,アルキンのアルリルシアン化のための効果的な経路を提供します.
- この反応は,高度に置換されたアリル系を構築するための強力な戦略を提供します.
- この方法論は,プラウノトールなどの複雑な天然製品の合成に適用できます.
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.
01:10Aldehydes and Ketones with HCN: Cyanohydrin Formation Mechanism
Cyanohydrins are formed when cyanide nucleophiles and carbonyl compounds like aldehydes and ketones react. A strong base, the cyanide ion, catalyzes cyanohydrin formation. The ions are generated from HCN under aqueous conditions. Once the cyanide ions are generated, the first step involves the nucleophilic attack of the cyanide ions on the electrophilic carbonyl carbon. This attack shifts the π electrons from the C=O to the oxygen atom forming the alkoxide ion intermediate. The alkoxide anion...
01:32Aldehydes and Ketones with HCN: Cyanohydrin Formation Overview
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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.
02:47Alkynes 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.
02:38Electrophilic 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.