不飽和O-アルキルヒドロキサマートの内分子酸化:ヒドロキシラクタムへの驚くほど多用途なエントリー
Duncan J Wardrop1, Edward G Bowen, Raymond E Forslund
1University of Illinois at Chicago, Department of Chemistry, 845 West Taylor Street, Room 4500, Chicago, Illinois 60607-7061, USA. wardropd@uic.edu
Journal of the American Chemical Society
|October 1, 2009
まとめ
新しい多用途な方法では,ヨウ素 (III) 媒介によるオキシアミデーションを用いて,5〜8基のヒドロキシラクタムを作製する. このステレオ特異的および地域選択的変換は,複雑な循環性アミド合成のための新しい合成経路を提供します.
科学分野:
- 有機化学 オーガニック・ケミストリー
- 合成方法論 合成方法論
- 薬用化学 薬用化学について
背景:
- ラクトームは,多くの医薬品に含まれる重要なヘテロサイクリック化合物です.
- 中規模のラクトーム (5〜8つの環) の効率的な合成は,合成上の課題であり続けています.
- 新しいサイクライゼーション戦略の開発は,多様なラクタム・スキャフォールドにアクセスするために不可欠です.
研究 の 目的:
- 5つから8つ構成のヒドロキシラクタムを合成するための多用途で効率的な方法を開発する.
- ラクタム形成のための新しいヨウ素 (((III)) 媒介オキシミダーション反応を探求する.
- この新しい合成変換のステレオ化学的および地域化学的結果を調査する.
主な方法:
- 未飽和O-アルキルヒドロキサマートのヨウ素 (III) 媒介によるオキシミデーションが利用された.
- シングレットニトロニウムとバイサイクルN-アシル-N-アルコキシアジリジニウムイオン中間物質を提案し,反応機構を調査した.
- 反応のステレオスペシフィシティと地域選択性を22の異なる基板で調べました.
主要な成果:
- 5~8基のヒドロキシラクタムの範囲を成功裏に準備しました.
- ヨウ素 ((III) 媒介によるオキシミデーションアプローチの汎用性を実証しました.
- ほとんどの試験症例で高いステレオスペシフィシティと地域選択性が観察され,予測可能な反応結果を示しています.
- 提案された中間物質に関するメカニズム的な洞察を提供した.
結論:
- 開発されたヨウ素 ((III) 媒介によるオキシミデーションは,ヒドロキシラクタム合成の強力で多用途な方法である.
- この方法では,ステレオ特異的で高度に地域選択的な経路で,価値ある5〜8つ構成の乳腺構造が得られます.
- この発見は,薬剤開発に関連する複雑なヘテロサイクリック化合物にアクセスするための新しい合成戦略に寄与しています.
関連する概念動画
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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.
Alkynes 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.
Oxidation 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.
Oxidation 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.
Acid-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...
Preparation of Epoxides
Overview
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of peroxy acids to...
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of peroxy acids to...


