1,2-ジケトンと単純なオレフィンによる触媒的分子間C-アルキル化:再利用可能な指向グループ戦略
Zhiqian Wang1, Brandon J Reinus, Guangbin Dong
1Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, USA.
Journal of the American Chemical Society
|August 15, 2012
まとめ
この研究は,オレフィンを用いたサイクルディケトンの新種のロジウム触媒Cアルキル化を導入しています. この効率的な方法は,合成を簡素化し,価値ある化合物を作成するためのよりグリーンな代替案を提供します.
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:
- ケトンアルファ-アルキレーションは,有機合成における基本的な変換である.
- 既存の方法は,しばしば厳しい条件やステキオメトリック反応剤を必要とします.
- C-アルキル化のための触媒的かつ効率的な方法の開発は,依然として重要な課題です.
研究 の 目的:
- 周期性1,2-ジケトンのロジウム触媒による新しい分子間C-アルキル化を開発する.
- 単純な末端オレフィンをアルキル化剤として利用する.
- 効率と持続可能性の向上のために,リサイクル可能な指導グループを雇う.
主な方法:
- 周期性1,2-ジケトンと末端オレフィン間のロジウム触媒反応.
- アミノピリジンをリサイクル可能な誘導基として使用し,インサイトでエナミンを形成する.
- ヴィニルC−H結合の活性化と,その後のC−アルキル化.
- 誘導群の裂け方と回復は,水解による.
主要な成果:
- 末端オレフィンによる周期性1,2-ジケトンのRh触媒による分子間C-アルキル化の最初の例.
- アリファティックオレフィン,アロマティックオレフィン,ビニルエステルを含む,広範な基板の適用範囲が実証されています.
- 1つの鍋で3-エチル-5-メチル-1,2-サイクロペンタディオンの合成が成功し,53%の収量で,以前の4段階の経路 (16%の収量) を大幅に上回りました.
結論:
- 開発された方法は,触媒ケトンアルファ-アルキル化のための効率的で汎用的な経路を提供します.
- リサイクル可能な指導グループ戦略は,持続可能性と原子経済を高めます.
- この研究は,未活性化オレフィンを用いた触媒性アルキル化の将来の発展の基礎をなしています.
関連する概念動画
01:22Alkenes 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.
02:24Reduction 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.
01:27Aldol Condensation with β-Diesters: Knoevenagel Condensation
The Knoevenagel condensation is an aldol-type reaction involving the condensation of aldehydes or ketones with active methylene compounds such as β-diesters to produce substituted olefins.
02:44Oxidation 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.
01:21Acid-Catalyzed α-Halogenation of Aldehydes and Ketones
By replacing an α-hydrogen with a halogen, acid-catalyzed α-halogenation of aldehydes or ketones yields a monohalogenated product
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
02:04Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
Diols are compounds with two hydroxyl groups. In addition to syn dihydroxylation, diols can also be synthesized through the process of anti dihydroxylation. The process involves treating an alkene with a peroxycarboxylic acid to form an epoxide. Epoxides are highly strained three-membered rings with oxygen and two carbons occupying the corners of an equilateral triangle. This step is followed by ring-opening of the epoxide in the presence of an aqueous acid to give a trans diol.