末端アルキネスによるMn触媒による芳香C-Hアルケニル化
Bingwei Zhou1, Hui Chen, Congyang Wang
1Beijing National Laboratory of Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
Journal of the American Chemical Society
|January 5, 2013
まとめ
この研究では,ターミナルアルキンを用いた最初のマンガン触媒C-Hアルケニル化が紹介されています. 効率的で選択的な反応により,抗マルコフニコフのE-オレフィンが生み出され,触媒的有機合成が進みます.
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:
- アロマティックC-H機能化は,複雑な有機分子の合成に不可欠です.
- C-Hアルケニル化のための効率的な触媒システムの開発は,依然として大きな課題です.
- マンガンの触媒は,貴金属触媒の費用対効果が高く,持続可能な代替手段を提供します.
研究 の 目的:
- 末端アルキンによる芳香C-Hアルケニル化のための最初のマンガン触媒メソッドを開発する.
- アルケニル化反応において,高い化学,地域,およびステレオ選択性を達成する.
- 実験的・計算的研究を用いて,触媒メカニズムを解明する.
主な方法:
- マンガネスブロミドカルボニル (MnBr(CO) 5とジサイクロヘキシアミン (Cy2NH) を含む単純な触媒システムを使用しました.
- 様々な末端アルキンで芳香C-Hアルケニル化反応を行った.
- 実験調査と密度関数理論 (DFT) の計算を行い,反応経路を理解しました.
主要な成果:
- 末端アルキンで初めてマンガン触媒による芳香C-Hアルケニル化が成功しました.
- この反応は,高い化学,地域,およびステレオ選択性で進行し,高収量で抗マルコフニコフのE構成オレフィンを生成しました.
- マンガンサイクルおよびアルキニルマンガネス種を含む主要な中間物質を特定しました.
- リンガンドからリンガンドへの水素転送とアルキニル補助C-H活性化が重要な触媒的ステップであることを決定しました.
結論:
- 操作的にシンプルで高効率のマンガン触媒C-Hアルケニル化プロトコルを確立しました.
- 開発された方法は,アンチ-マルコヴニコフニコフの地域選択性を持つE-オレフィンを作るための貴重なツールを提供します.
- 機械学的洞察は,マンガンで触媒化されたC-H活性化および機能化反応のより広い理解に貢献します.
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.
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02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Introduction
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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.
02:47Alkynes 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.
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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.
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