パラジウム (((0)) -触媒化されたC (((sp3) -H結合のアルキニル化
Jian He1, Masayuki Wasa, Kelvin S L Chan
1Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States.
Journal of the American Chemical Society
|February 15, 2013
まとめ
この研究では,パラジウム触媒を用いたアリファティックアミドをアルキニル化するための新しい方法が紹介されています. このブレークスルーにより,以前は反応しないC ((sp ((3)) -Hボンドの活性化が可能になり,合成の可能性が広がった.
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
- 合成方法論 合成方法論
背景:
- アリファティックアミドのC ((sp ((3)) -H結合を活性化することは困難です.
- アルキニル化反応は,複雑な有機分子を合成するのに極めて重要です.
研究 の 目的:
- アリファティックアミドにおけるβ-C(sp(3)) -H結合のアルキニル化のための新しい方法の開発.
- この変換のためのパラジウム触媒の使用を調査する.
主な方法:
- N-ヘテロサイクリックカルベン (NHC) とフォスフィン (PR3) リガンドを含むパラジウム (((0) 触媒を使用しています.
- カップリングパートナーとしてアルキニルハライドを使用した.
- C ((sp ((3)) -Hボンドの触媒活性化を研究した.
主要な成果:
- アリファティックアミドにおけるβ-C(sp(3)) -H結合のアルキニル化に成功しました.
- Pd(0) /NHCおよびPd(0) /PR3触媒システムの有効性を実証しました.
- この研究は,C (sp (3)) -H結合活性化のための[AlkynylPd (II) L (n) ]複合体の最初の使用を表しています.
結論:
- アリファティックアミドをアルキニル化する効率的な触媒システムを開発した.
- オーガノパラジウム複合体を用いてC(sp(3)) -H結合活性化のための新しい先例を確立しました.
- この発見は,有機合成のための貴重なツールを提供します.
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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.
02:27Preparation 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.
02:38Electrophilic 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.
02:47Alkynes 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.
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.