コバルト媒介によるC(2) とC(1) ディエンのエナチオセレクティブ合成
W Christopher Boyd1, Mark R Crimmin, Lauren E Rosebrugh
1Department of Chemistry, University of California, Berkeley, California 94720, United States.
Journal of the American Chemical Society
|November 2, 2010
まとめ
この研究では,コバルト触媒とキラル塩基を用いたアルケンの非対称C-H機能化が報告されています. この方法は,高い選択性を持つ有価なダイエネリガンドのエナチオセレクティブ合成を可能にします.
科学分野:
- 有機化学 オーガニック・ケミストリー
- 有機金属化学 有機金属化学
- アシンメトリック・カタリシス
背景:
- C-H機能化は,有機合成における重要な変換である.
- 非対称な触媒は,エナチオメリックに純粋な化合物の合成を可能にします.
- ノルボルネンとノルボルナディエンは,機能化のための多用途のサイクルアルケーンです.
研究 の 目的:
- ノルボルネンとノルボルナディエンの非対称的なC-H機能化のための新しい方法を開発する.
- コバルト-ニトロシル複合体を反応性中間体として利用する.
- C(2) -とC(1) -対称のダイエネリガンドのエナチオセレクティブ合成を達成するために.
主な方法:
- 非対称なC-H機能化反応は[{η(5)-((t) BuMe(2) Si) C(5) H(4)}Co(NO) ((2)) ]によって媒介される.
- エナティオピュールアンモニアム塩とNaHMDSから新しいキラル塩基混合物の使用.
- C (((s)) アルケンの非対称化に適用される.
主要な成果:
- 機能化では高い地域選択性 (3.7-20:1 anti/syn) が達成されました.
- ほぼ完璧なダイアステレオ選択性 (>99:1 dr) が観察されました.
- 合成されたダイネリガンドの高いエナチオセレクティブ性 (90-96% ee) が得られた.
結論:
- 開発された方法は,エナチオメリックに濃縮されたダイエネリガンドへの効率的なアクセスを提供します.
- この研究は,アルケンの非対称化のための非対称C-H機能化の新しい応用を示しています.
- この方法論は,複雑なキラル分子を構築するための強力なツールを提供します.
関連する概念動画
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Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
Diels–Alder reactions between cyclic dienes locked in an s-cis configuration and dienophiles yield bridged bicyclic products.
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The Diels–Alder reaction brings together a diene and a dienophile to form a six-membered ring. Both components have unique characteristics that influence the rate of the reaction.
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Characteristics of the diene
Conformation
The simplest example of a diene is 1,3-butadiene, an acyclic conjugated π system. At room temperature, the molecule exists as a mixture of s-cis and s-trans conformers by virtue of rotation around the carbon–carbon single bond. Although the s-trans isomer is more stable, the...
Cycloaddition Reactions: Overview
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.
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