エテノリシスの高度選択性のあるルテニウムメタテシス触媒
Renee M Thomas1, Benjamin K Keitz, Timothy M Champagne
1The Arnold and Mabel Beckman Laboratories of Chemical Synthesis, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
Journal of the American Chemical Society
|April 23, 2011
まとめ
新しいN-アリル,N-アルキル,N-ヘテロサイクリックカルベン (NHC) ルテニウム触媒は,メチルオレアエステノリシスに対して高い選択性を提供します. これらの触媒は,低負荷で優れた収量と安定性を提供し,オレフィン転化アプリケーションを進める.
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
- マテリアルサイエンス 材料科学
背景:
- オレフィンメタテシスは有機合成の強力なツールです.
- ルテニウム触媒は広く使用されているが,選択性が欠けていることが多い.
- N-ヘテロサイクリックカルベン (NHC) リガンドは,触媒の性能を向上させます.
研究 の 目的:
- エテノリシスのための高度に選択的なN-Aryl,N-alkyl NHCルテニウム触媒を開発する.
- 低負荷で触媒の安定性と効率を調査する.
- ステリック障害に基づいて触媒の性能を比較する.
主な方法:
- 新しいNHCルテニウムメタテシス触媒の合成と特徴付け.
- メチルオレアートのエセノリシスで,運動製品の選択性を評価する.
- 端末オレフィンのクロスメタテシスで,熱力学的製品と運動的製品に対する触媒の好みを評価する.
- 低触媒負荷 (<500 ppm) で触媒の安定性,収量,および周回数の分析.
主要な成果:
- キネティックエテナリシス製品では,最高95%の選択性を達成しました.
- メチリデンの種として異常に好みがあり,繁殖に対する安定性を示した.
- 低触媒負荷で良好な生産量とターンオーバー数を得ました.
- ステリカルに阻害されたNHC置換剤は,より高い選択性,安定性,およびより長い触媒寿命をもたらしました.
- より選択的な触媒は,クロスメタテシス産物変換が低い安定状態に達した.
結論:
- N-Aryl,N-alkyl NHC ルテニウム触媒は,選択的エテナリシスの重要な進歩を表しています.
- 触媒の設計,特にNHC置換物のステリック阻害は,選択性と安定性を最適化するために不可欠です.
- これらの発見は,メタテシスを用いてより効率的かつ制御されたオレフィン変換を可能にします.
関連する概念動画
01:13Olefin Metathesis Polymerization: Overview
Recently, the development of olefin metathesis polymerization advanced the field of polymer synthesis. Simply put, the reorganization of substituents on their double bonds between two olefins in the presence of a catalyst is known as the olefin metathesis reaction. The use of metathesis reaction for polymer synthesis is called olefin metathesis polymerization.
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists of a...
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists of a...
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...
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.
02:44Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
Alkenes are converted to 1,2-diols or glycols through a process called dihydroxylation. It involves the addition of two hydroxyl groups across the double bond with two different stereochemical approaches, namely anti and syn. Dihydroxylation using osmium tetroxide progresses with syn stereochemistry.
01:25Radical Anti-Markovnikov Addition to Alkenes: Overview
The addition of hydrogen bromide to alkenes in the presence of hydroperoxides or peroxides proceeds via an anti-Markovnikov pathway and yields alkyl bromides.
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...