アルケンのトランジションメタルフリー酸化で,アリルディアゾニウム塩とTEMPONaNaが用いられる
Marcel Hartmann1, Yi Li, Armido Studer
1Institute of Organic Chemistry, University of Münster, Corrensstrasse 40, 48149 Münster, Germany.
Journal of the American Chemical Society
|September 27, 2012
まとめ
新しい方法では,簡単に手に入るTEMPONaとアリルディアゾニウム塩を使用して,アリルラジカルを作成します. これらのラジカルはアルケーンと反応し,穏やかで金属のない条件下では効率的にオキシアリル化製品を形成します.
科学分野:
- 有機化学 オーガニック・ケミストリー
- ラジカル・ケミストリー (Radical Chemistry) とは
背景:
- アリルラジカルは重要な合成中間物質である.
- アリル基の生成のための以前の方法は,しばしば厳しい条件や移行金属を必要とします.
研究 の 目的:
- アリルラジカルを生成するための軽度で金属のない方法を開発する.
- アルケーンにアリルラジカルを添加することにより,オキシアリル化製品を合成する.
主な方法:
- ナトリウム (2,2,6,6-テトラメチルピペリジン-1-オキシル) (TEMPONa) とアリルディアゾニウム塩との反応.
- TEMPOを使用してアルケーンで生成されたアリルラジカルをトラップする.
主要な成果:
- アリル基のクリーン生成とTEMPO.
- オキシアリル化製品の良好から優れた収量.
- 幅広い機能群の互換性が観察されました.
結論:
- 開発された方法は,オキシアリレーション製品への簡単で効率的な経路を提供します.
- 反応は,過渡金属のない穏やかな条件下で進行します.
- このアプローチは,機能群の許容性により,複雑な分子に適しています.
さらに関連する動画
関連する概念動画
01:14Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic SN1
Treating arylamines with nitrous acid gives aryldiazonium salts that are effective substrates in nucleophilic aromatic substitution reactions. The diazonio group in these salts can be easily displaced by different nucleophiles, yielding a wide variety of substituted benzenes. The leaving group departs as nitrogen gas, and this easy elimination is the driving force for the substitution reaction.
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo, or cyano...
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo, or cyano...
01:371° Amines to Diazonium or Aryldiazonium Salts: Diazotization with NaNO2 Mechanism
Nitrous acid is a relatively weak and unstable acid prepared in situ by the reaction of sodium nitrite and cold, dilute hydrochloric acid. In an acidic solution, the nitrous acid undergoes protonation when it loses water to form a nitrosonium ion—an electrophile. Nitrous acid reacts with primary amines to give diazonium salts. The reaction is called diazotization of primary amines.
01:19Diazonium Group Substitution: –OH and –H
Nitrous acid, a weak acid, is prepared in situ via the reaction of sodium nitrite with a strong acid under cold conditions. This nitrous acid prepared in situ reacts with primary arylamines to form arenediazonium salts. Such reactions are known as diazotization reactions. As shown in Figure 1, the formation of arenediazonium salts begins with the decomposition of nitrous acid in an acidic solution to give nitrosonium ions.
01:33Carboxylic Acids to Methylesters: Alkylation using Diazomethane
Carboxylic acids react with diazomethane in an ether solvent via alkylation at the carboxylate oxygen atom to give methyl esters of the corresponding acid with excellent yields.
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.
01:20Diazonium Group Substitution with Halogens and Cyanide: Sandmeyer and Schiemann Reactions
Arenediazonium substitution reactions occur when the diazonium group is substituted by various functional groups such as halides, hydroxyl, nitrile, etc. For instance, arenediazonium salts react with copper(I) salts of chloride, bromide, or cyanide to form corresponding aryl chlorides, bromides, and nitriles. These reactions are named Sandmeyer reactions. Although the mechanism of this reaction is complicated, as illustrated in Figure 1, they are believed to progress via an aryl copper...