アルキナルの触媒的非対称性アリラティブサイクリング:効率的な触媒として,フォスフィンフリーロジウム/ダイネ複合体
Ryo Shintani1, Kazuhiro Okamoto, Yusuke Otomaru
1Department of Chemistry, Graduate School of Scienece, Kyoto University, Sakyo, Kyoto 606-8502, Japan.
Journal of the American Chemical Society
|January 6, 2005
まとめ
ロジウム触媒による新しいアリラティブサイクリング法により,アルキナルから複雑な分子を効率的に合成することができます. 非対称的な変種を含むこのフォスフィンフリーのアプローチは,炭素-炭素結合形成のための多用途な経路を提供します.
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:
- 触媒性アリラティブサイクリングは,循環性有機分子を構築するための重要な変換です.
- 効率的で選択的な触媒システムの開発は,有機合成における重要な課題です.
研究 の 目的:
- アルキナルのアリレーティブサイクリングのための新しい,フォスフィンのない,ロジウムベースの触媒システムを開発する.
- この反応の非対称的な変種をキラルリンガンドを使用して確立する.
- 他の不飽和基板のための開発された触媒の範囲を調査する.
主な方法:
- フォスフィンフリーロジウム/ダイエン複合体を触媒として利用する.
- C2対称性キラルビサイクロ[2.2.2]オクタディエネリガンドを用いて,非対称性カタリシスを行う.
- アルキナル,アルキノン,エニンなどの様々な基質との反応を調査する.
主要な成果:
- アルキナルの触媒的アリラティブサイクリングの成功開発.
- キラルなビサイクロ[2.2.2]オクタディエネリガンドを用いたエナンチオセレクティブの変種を達成した.
- アルキノンとエニンで複数のC-C結合を1つのステップで形成する,触媒の有効性を実証しました.
結論:
- 開発されたフォスフィンフリーロジウム/ダイネ触媒システムは,アリレーティブサイクライゼーションの効率的な方法を提供します.
- 非対称な触媒は,キラルサイクル化合物の合成のための新しい道を開く.
- この方法論は汎用性があり,不飽和基質の範囲に適用でき,複雑な分子構造への迅速なアクセスを可能にします.
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...
Reduction 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.
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
Alkenes 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.
Aldehydes and Ketones to Alkenes: Wittig Reaction Mechanism
The Wittig reaction, which converts aldehydes or ketones to alkenes using phosphorus ylides, proceeds through a nucleophilic addition‒elimination process.
The reaction begins with the nucleophilic addition between a phosphorus ylide and the carbonyl compound. Due to its carbanionic character, phosphorus ylide acts as a strong nucleophile and attacks the electrophilic carbonyl group. This generates a charge-separated dipolar intermediate called betaine. The negatively charged oxygen atom and...
The reaction begins with the nucleophilic addition between a phosphorus ylide and the carbonyl compound. Due to its carbanionic character, phosphorus ylide acts as a strong nucleophile and attacks the electrophilic carbonyl group. This generates a charge-separated dipolar intermediate called betaine. The negatively charged oxygen atom and...
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.

![[(DPEPhos)(bcp)Cu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F59739.jpg&w=3840&q=50)
