末端オレフィンから線形α,β不飽和ケトン:Pd (II) /高価ヨウ素共触媒によるワッカーの酸化-脱水化
Marinus A Bigi1, M Christina White
1Roger Adams Laboratory, Department of Chemistry, University of Illinois, Urbana, Illinois 61801, USA.
Journal of the American Chemical Society
|May 16, 2013
まとめ
新しい軽度のワッカーの酸化-脱水反応は,オレフィンから不飽和ケトンを生成するために,パラジウムと高価ヨウ素を使用します. この効率的な方法は,良い収穫量と機能グループ耐性を提供します.
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:
- ワッカーの酸化は,オレフィンをケトンに変換するために不可欠な変換です.
- より穏やかで効率的な触媒システムの開発は,有機合成の重要な目標です.
- タンデム反応は,合成経路を合理化し,全体的な効率性を向上させる利点を提供します.
研究 の 目的:
- α,β不飽和ケトンを合成するための温和で効率的なワッカー酸化-脱水反応のタンデムを開発する.
- パラジウム (II) と高価ヨウ素の共触媒の使用を軽度な条件下で調査する.
- 端末オレフィンから直接高収量と選択性を達成する.
主な方法:
- ワッカーの酸化脱水配列を組み合わせる.
- パラジウム (((II) を触媒として,高価ヨウ素を共触媒として利用する.
- 反応は温和な温度 (35°C) で,ブロンステッド酸なしで実施する.
主要な成果:
- 線形アリルとアルキル α,β-不飽和ケトンの合成が成功しました.
- 平均75パーセントの順位で良い収穫を達成しました.
- 優れた機能的グループ耐性,化学選択性,ステレオ選択性を示した.
- 脱水化段階における高価ヨウ素共触媒の重要な役割を確認した.
結論:
- 新しい,軽いタンドームのワッカー酸化-脱水酸化プロトコルが確立されました.
- 開発された方法は,単純なオレフィンから貴重なα,β不飽和ケトンに直接アクセスできます.
- 触媒システムは広範な適用性と高い選択性を示しており,有機合成の貴重なツールとなっています.
関連する概念動画
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.
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.
02:21Oxidation of Alkenes: Syn Dihydroxylation with Potassium Permanganate
Alkenes can be dihydroxylated using potassium permanganate. The method encompasses the reaction of an alkene with a cold, dilute solution of potassium permanganate under basic conditions to form a cis-diol along with a brown precipitate of manganese dioxide.
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.
01:22Reactions of Aldehydes and Ketones: Baeyer–Villiger Oxidation
Baeyer–Villiger oxidation converts aldehydes to carboxylic acids and ketones to esters. The reaction uses peroxy acids or peracids and is often catalyzed by acid. The reaction is named after its pioneers, Adolf von Baeyer and Victor Villiger. The reaction is achieved by a wide range of peracids such as m-chloroperoxybenzoic acid (mCPBA), perbenzoic acid (C6H5COOOH), peracetic acid (CH3COOOH), hydrogen peroxide (H2O2), and tert-butyl hydroperoxide (t-BuOOH).
The carbonyl center is activated by...
The carbonyl center is activated by...
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
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.