オーガノカタリティック・エナチオセレクティブ・フォーマルC ((sp ((2)) -Hアルキレーション
Madhu Sudan Manna1, Santanu Mukherjee
1Department of Organic Chemistry, Indian Institute of Science , Bangalore 560012, India.
Journal of the American Chemical Society
|January 1, 2015
まとめ
新しい有機触媒法により,エナチオセレクティブC-Hアルキル化が可能になった. このプロセスは,容易に入手可能なニトロアルカンを用いて,四次元のステレオジェニックな中心を持つ複雑なカーボサイクルを効率的に作成します.
科学分野:
- 有機化学 オーガニック・ケミストリー
- アシンメトリック・カタリシス
- 合成方法論 合成方法論
背景:
- 複雑なカルボサイクルの構造を作り出すための効率的な方法の開発は,有機合成において極めて重要です.
- エナチオセレクティブ・コントロール,特に四次元のステレオジェニック・センターの達成は,依然として大きな課題です.
- オルガノカタリシスは,非対称な変換のための金属のない代替手段を提供します.
研究 の 目的:
- 新しい有機触媒のエナチオセレクティブ形式のC ((sp2) -Hアルキル化反応を報告する.
- この触媒システムを用いて,プロキラルサイクロペンテネディオンの脱対称化を実証する.
- 遠隔の全炭素四分型ステレオジェニックセンターで多用途の5つ構成のカーボサイクルを合成する.
主な方法:
- 器官触媒として二機能的三次アミノウレア誘導体を利用した.
- 空気安定で安価なニトロアルカンをアルキル化剤として使用した.
- プロキラル2,2-非置換サイクロペテン-1,3-ダイオンのアルキラティブデシメトリゼーションを調査した.
主要な成果:
- ターゲットカルボサイクルの形成において優れたエナチオセレクティビティを達成した.
- 四次性ステレオジェニックセンターを含む5つ組のカーボサイクルを成功裏に生成しました.
- この反応は,正式なC(sp2) -Hアルキル化経路を経由して進行する.
結論:
- 開発された有機触媒システムは,エナチオメリックに濃縮されたカルボサイクルの効率的な経路を提供します.
- この方法論は,複雑な分子構造を構築するための貴重なツールを提供します.
- ニトロアルカンをアルキル化剤として使用することは,このアプローチの実用性と持続可能性を強調しています.
関連する概念動画
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
4.1K
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...
4.1K
01:10α-Alkylation of Ketones via Enolate Ions
4.2K
Ketones with α protons are deprotonated by strong bases like lithium diisopropylamide (LDA) to form enolate ions. The anion is stabilized by resonance, and its hybrid structure exhibits negative charges on the carbonyl oxygen and the α carbon. This ambident nucleophile can attack an electrophile via two possible sites: the carbonyl oxygen, known as O-attack, or the α carbon, known as C-attack. The nucleophilic attack via the carbanionic site is preferred. This is due to the...
4.2K
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
9.7K
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.
9.7K
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
22.2K
Introduction
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
22.2K
01:25Radical Anti-Markovnikov Addition to Alkenes: Overview
4.4K
The addition of hydrogen bromide to alkenes in the presence of hydroperoxides or peroxides proceeds via an anti-Markovnikov pathway and yields alkyl bromides.
4.4K
02:36Regioselectivity and Stereochemistry of Hydroboration
9.9K
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...
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...
9.9K