エナチオセレクティブモノヒドロゲネーションによるメソサイクルイミドの脱対称化
Satoshi Takebayashi1, Jeremy M John, Steven H Bergens
1Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2.
Journal of the American Chemical Society
|August 26, 2010
まとめ
チラルのサイクルイミドは,不対称な水素化を経て,ルテニウム触媒を用いて高エナチオ選択性を持つヒドロキシラクタムを生成する. この脱対称化反応は,複数のステレオセンターを効率的に生成し,複雑な分子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
- カタリシス カタリシス カタリシス
- アシンメトリック・シンセシス
背景:
- 周期性イミドは,医薬品における重要な構造モチーフである.
- キラルセンターを作成するための効率的な方法は,有機合成において極めて重要です.
研究 の 目的:
- メソサイクルイミドの非対称な水素化のための高度なエナチオセレクティブの方法を開発する.
- 複数のステレオセンターを生成するメソサイクリックイミドの非対称化を調査する.
主な方法:
- トランス[Ru((R) -BINAP) ((H) ((2) (((R,R) -dpen) ]および関連する触媒を用いたメソサイクルイミドの非対称な水素化.
- テトラヒドロフラン (THF) の塩基媒介反応.
- その後,ヒドロキシラクタムの機能化により,イミニウムイオンを形成し,インデネを添加する.
主要な成果:
- メソサイクリックイミドをヒドロキシラクタムに単水素化することで,高いエナチオセレクティブ性 (88~97% ee) を得ている.
- 高い反抗グループと化学選択性を示した.
- 単一の反応配列で最大7つのステレオジェニックセンターを成功裏に作成しました.
結論:
- 開発された触媒システムは,メソサイクルイミドの非対称化のための効率的な経路を提供します.
- この方法は,複数のキラルセンターを持つ複雑な分子の立体選択合成を可能にします.
関連する概念動画
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...
Diels–Alder Reaction Forming Cyclic Products: Stereochemistry
The Diels–Alder reaction is one of the robust methods for synthesizing unsaturated six-membered rings. The reaction involves a concerted cyclic movement of six π electrons: four π electrons from the diene and two π electrons from the dienophile.
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.
Regioselectivity and Stereochemistry of Hydroboration
A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
Oxidation 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.
Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
The rate of acid-catalyzed hydration of alkenes depends on the alkene's structure, as the presence of alkyl substituents at the double bond can significantly influence the rate.


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