アルデヒドとアルキネのニッケル触媒による還元結合における地域制御のための一般的な戦略
Hasnain A Malik1, Grant J Sormunen, John Montgomery
1Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, USA.
Journal of the American Chemical Society
|April 17, 2010
まとめ
新しい触媒戦略により,アルデヒド-アルキン還元結合における地域選択性を制御することができる. この方法は,基板バイアスから独立して,多様な基板のためのいずれかの結果の選択を可能にします.
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:
- 還元結合における地域選択性は,合成に不可欠である.
- 既存の方法は,しばしば基質を指示するグループやバイアスに依存しています.
- 地域選択性を制御するための普遍的な戦略が必要である.
研究 の 目的:
- 地域選択性アルデヒド-アルキン還元結合のための触媒制御戦略を開発する.
- 地域化学的結果に対する予測可能な制御を達成するために.
- サブストラットバイアスなしに,いずれかの地域化学的結果の選択を可能にするために.
主な方法:
- 補完的なサイクロプロペニリデンカルベンとN-ヘテロサイクリックカルベンのリガンドを使用しています.
- これらのリガンドを使用して,触媒の行動を制御します.
- この戦略を様々なアルキン基板に適用する.
主要な成果:
- アルデヒド-アルキンの還元結合において,触媒制御された地域選択性が実証されている.
- 幅広い基板に対して予測可能な地域化学的結果を達成しました.
- 異なるリガンドタイプを使用して地域選択性を逆転させる能力を示した.
結論:
- 還元結合における地域選択性を制御するための新しく汎用的な戦略が確立されています.
- コンプリメンタリー・リガンドアプローチは,前例のない反応結果のコントロールを提供します.
- この方法は,合成化学者のための強力なツールを提供し,以前の戦略の限界を克服します.
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.
01:27Vicinal Diols via Reductive Coupling of Aldehydes or Ketones: Pinacol Coupling Overview
Wilhelm Rudolph Fittig discovered the pinacol coupling reaction in 1859. It is a radical dimerization reaction and involves the reductive coupling of aldehydes or ketones in the presence of hydrocarbon solvent to yield vicinal diols.
02:17Reduction 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...
01:22Alkenes via Reductive Coupling of Aldehydes or Ketones: McMurry Reaction
The radical dimerization of ketones or aldehydes gives vicinal diols through a pinacol coupling reaction. However, the behavior of titanium metals used for the reaction as a source of electrons is unusual. When the reaction is carried out in the presence of titanium, diols can be isolated at low temperatures. Else titanium further reacts with diols, forming alkenes through the McMurry reaction.
02:13Reduction 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...
02:17Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
If a set of reactants can yield multiple constitutional isomers, but one of the isomers is obtained as the major product, the reaction is said to be regioselective. In such reactions, bond formation or breaking is favored at one reaction site over others.
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...