狭い幾何学におけるオレフィンメタテシス:選択的なマクロサイクリングに向けたバイオミメティックアプローチ
Felix Ziegler, Johannes Teske, Iris Elser
1Institute of Thermodynamics and Thermal Process Engineering , University of Stuttgart , Pfaffenwaldring 9 , D-70569 Stuttgart , Germany.
Journal of the American Chemical Society
|November 8, 2019
まとめ
この研究は,環閉メタテシスにおけるマクロサイクリングの選択性を高めるために,オーダーされたメソポラスシリカ内の空間的閉じ込みを用いたバイオミメティックアプローチを導入している. この方法は,オリゴマーの形成を大幅に減らし,望ましいマクロサイクル製品の収量を改善します.
科学分野:
- 有機化学
- 材料科学
- 化学工学
背景:
- マクロサイクル合成は,しばしば望ましくないオリゴマーの形成によって妨げられます.
- マクロサイクライゼーション反応において,特に高い基板濃度において,高い選択性を達成することは,依然として課題である.
研究 の 目的:
- マクロサイクライゼーションの選択性を改善するために,空間的制限を使用するバイオミメティック戦略を開発する.
- マクロサイクライゼーションとオリゴメリゼーションの比率に対する毛穴の大きさと表面の変化の影響を調査する.
主な方法:
- 特定の孔径のオーダーメイドメソポラスシリカ内で固定されたオレフィンメタテシス触媒を使用します.
- 様々なダイエンの環閉メタテシスを,高濃度基板 (25 mMまで) で実行する.
- 孔の表面をディメトオキシジメチルシランで修正し 孔の大きさと表面の極性を調整します
主要な成果:
- マクロ・モノ・サイクリング (MMC) とオリゴメリゼーション (O) の比率は,同質な触媒を用いて0. 55 (35% MMC) から,閉じ込められた触媒を用いて1. 49 (60% MMC) に大幅に増加した.
- MMC/O比率と基板と毛穴の大きさの比率との間には直接的な相関が確立された.
- 表面改変により,MMC/O比率が2.2 (>68% MMC) に増加し,調節可能な選択性を示した.
結論:
- メソポラス材料内の空間的閉じ込めは,マクロサイクリングの選択性を高めるための効果的な戦略です.
- メソポラスシリカの表面改変は,孔環境と相互作用を制御することによって選択性の微調整を可能にします.
- このアプローチは,伝統的な方法の限界を克服し,マクロサイクルを効率的に合成するための有望な経路を提供します.
関連する概念動画
Olefin Metathesis Polymerization: Overview
2.5K
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...
2.5K
Olefin Metathesis Polymerization: Acyclic Diene Metathesis (ADMET)
2.2K
Acyclic diene metathesis polymerization or ADMET polymerization involves cross-metathesis of terminal dienes, such as 1,8-nonadiene, to give linear unsaturated polymer and ethylene. As ADMET is a reversible process, the formed ethylene gas must be removed from the reaction mixture to complete the polymerization process.
Similar to cross-metathesis, ADMET also involves the formation of metallacyclobutane intermediate by [2+2] cycloaddition of one of the double bonds of a terminal diene with...
Similar to cross-metathesis, ADMET also involves the formation of metallacyclobutane intermediate by [2+2] cycloaddition of one of the double bonds of a terminal diene with...
2.2K
Olefin Metathesis Polymerization: Ring-Opening Metathesis Polymerization (ROMP)
3.1K
Ring-opening metathesis polymerization or ROMP involves strained cycloalkenes as starting materials. The mechanism of ROMP proceeds by reacting cycloalkene with Grubbs catalyst to give metallacyclobutane intermediate which undergoes a ring-opening reaction to form new carbene. The new carbene reacts with another molecule of cycloalkene. Repetition of these steps leads to the formation of an unsaturated open-chain polymer product. All these steps are reversible, however, relieving the ring...
3.1K
Cycloaddition Reactions: Overview
3.3K
Cycloadditions are one of the most valuable and effective synthesis routes to form cyclic compounds. These are concerted pericyclic reactions between two unsaturated compounds resulting in a cyclic product with two new σ bonds formed at the expense of π bonds. The [4 + 2] cycloaddition, known as the Diels–Alder reaction, is the most common. The other example is a [2 + 2] cycloaddition.
3.3K
Thermal Electrocyclic Reactions: Stereochemistry
2.4K
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
2.4K
Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
5.3K
Diels–Alder reactions between cyclic dienes locked in an s-cis configuration and dienophiles yield bridged bicyclic products.
5.3K


