アルケンの金属フリーオキシアミネーションには,ヒドロキサミ酸を用いてアルケンを酸化する
Valerie A Schmidt1, Erik J Alexanian
1Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA.
Journal of the American Chemical Society
|July 8, 2011
まとめ
この研究では,アミドキシルラジカルとジソプロピルアゾジカルボキシラート (DIAD) を使用した金属フリーアルケンの酸化アミネーション法が導入されています. このプロセスは,サイクルアルケンのトランスオキシアミン化製品に対する高いステレオ選択性を達成します.
科学分野:
- 有機化学 オーガニック・ケミストリー
- 合成化学 合成化学とは
背景:
- アルケンのオキシアミネーションは,有機合成における重要な変換である.
- 既存の方法は,しばしば金属触媒を必要とするか,ステレオ選択性が欠けている.
研究 の 目的:
- アルケンのオキシアミン化のための新しい金属のないアプローチを開発する.
- アルケンの機能不全における高い地域性およびステレオ選択性を達成する.
主な方法:
- アミドキシルラジカルを利用した,ラジカル媒介反応である.
- ダイソプロピルアゾジカルボキシラート (DIAD) をラジカルトラップとして使用.
- 分子内循環化戦略である.
主要な成果:
- メタルフリーアルケンのオキシアミネーションが成功しました.
- 高い地域選択性があり,単一の地域同位体を生成します.
- サイクルアルケンのトランスオキシアミネーション産物の立体選択合成.
結論:
- 記述された方法は,金属フリーアルケンのオキシアミネーションのための新しい経路を提供します.
- それは,高いステレオコントロールを持つ貴重なトランスオキシアミナーション製品へのアクセスを提供します.
- これは既存のシス・セレクティブ・オキシアミネーション法を補完するものです.
関連する概念動画
02:01Alkynes to Carboxylic Acids: Oxidative Cleavage
Alkynes undergo oxidative cleavage in the presence of oxidizing reagents like potassium permanganate and ozone. The triple bond — one σ bond and two π bonds — is completely cleaved, and the alkyne is oxidized to carboxylic acids. When warm and basic aqueous potassium permanganate is used as an oxidizing agent, alkynes are first converted to carboxylate salts via an unstable α-diketone intermediate. Further, a mild acid treatment protonates the carboxylate anions generating free carboxylic acid...
01:46Oxidative Cleavage of Alkenes: Ozonolysis
In ozonolysis, ozone is used to cleave a carbon–carbon double bond to form aldehydes and ketones, or carboxylic acids, depending on the work-up.
Ozone is a symmetrical bent molecule stabilized by a resonance structure.
Ozone is a symmetrical bent molecule stabilized by a resonance structure.
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.
03:08Hydroboration-Oxidation of Alkenes
In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.
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...
02:44Oxidation 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.