アリル塩化物からパラジウム触媒による分子内アルカンC-Hアリレーション
Sophie Rousseaux1, Michaël Davi, Julien Sofack-Kreutzer
1Centre for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N 6N5, Canada. srous100@uottawa.ca
Journal of the American Chemical Society
|August 5, 2010
まとめ
この研究では,アリル塩化物を用いて,パラジアム触媒による効率的な分子内C ((sp ((3)) -Hアリレーションを導入し,多様な循環化合物を生成します. リガンドと条件の最適化により,有価なサイクロブタレネス,インダネスなどの選択的合成が可能になります.
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
- 合成方法論 合成方法論
背景:
- パラジウムで触媒化されたC-H活性化は,有機合成の強力なツールです.
- 分子内C ((sp ((3)) -Hアリレーションは,循環構造への直接的な経路を提供します.
- 以前の方法は,しばしば基質の範囲や反応条件によって制限されていた.
研究 の 目的:
- (ヘテロアリル塩化物) の効率的で一般的なパラジアム触媒化された分子内C ((sp ((3)) -Hアリレーションを開発する.
- 簡単に入手可能なアリルおよびヘテロアリル塩化物を利用することによって,C ((sp ((3)) -Hアリレーションの範囲を拡大する.
- 様々な有価な循環性化合物の高収量と選択性を達成するために.
主な方法:
- パラジウムリガンド (P{t}Bu{3}),PCyp{3},PCy{3}) および塩基/溶媒組み合わせ (K{2}CO{3}/DMF,C{2}CO{3}/ピヴァリック酸/メシチレン) のスクリーニング.
- 反応条件の最適化により,異なる製品クラスにアクセスできます.
- 反応のメカニズムと選択性を明らかにするための計算研究 (DFT (((B3PW91)).
主要な成果:
- (ヘテロ) アリル塩化物の効率的で一般的なパラジウム触媒化された分子内C ((sp ((3)) -Hアリレーションの最初の例です.
- サイクロブタレネス,インダネス,インドリネス,ジヒドロベンゾフランス,インダノネスの合成が成功しました.
- 二次/三次よりもプライマリC-Hボンドの地域選択性が実証され,5つのメンバーのリング形成を好む.
- 40以上の成功したC-Hアリレーション例が報告されています.
結論:
- 開発された方法論は,アリル塩化物から貴重な周期性化合物への汎用的な経路を提供します.
- リンガンドと塩基/溶媒の選択は,製品の結果と生産量を制御するために重要です.
- 計算分析は,C-H活性化が速度決定因子であることを確認し,C-Hアゴスティック相互作用が地域選択性における役割を強調しています.
さらに関連する動画
関連する概念動画
Reduction 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.
Preparation 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.
Electrophilic 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.
Reduction of Alkenes: Catalytic Hydrogenation
Alkenes undergo reduction by the addition of molecular hydrogen to give alkanes. Because the process generally occurs in the presence of a transition-metal catalyst, the reaction is called catalytic hydrogenation.
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the surface of...
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the surface of...
Halogenation of Alkenes
Halogenation is the addition of chlorine or bromine across the double bond in an alkene to yield a vicinal dihalide. The reaction occurs in the presence of inert and non-nucleophilic solvents, such as methylene chloride, chloroform, or carbon tetrachloride.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...


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