アルキルボロンエステルのステレオ特異的変換は,直接ボロンから亜鉛への変金属化によって可能になる.
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PubMedで要約を見る
まとめ
この要約は機械生成です。チラルのオルガノボロンエステルは,ステレオレテンティブ伝達によって効率的に安定したチラルのオルガノシン反応剤に変換されます. これらの反応剤は,ステレオ固有の二酸化炭素反応,クロスカップリング,トリフローロメチル化を可能にします.
科学分野
- 有機化学
- 有機金属化学
- ステレオ化学
背景
- チラルの二次オルガノボロンエステルは,有価な合成中間物質である.
- ステレオ選択的機能化のための方法の開発は極めて重要です.
研究 の 目的
- キラル二次オルガノシン反応剤を合成するためのステレオレントの方法を開発する.
- これらの新種の有機亜鉛化合物の 合成有用性を探求する.
主な方法
- テート-ブチルチウムでキラル二次オルガンボロンエステルの活性化.
- ジンクアセテートまたはジンク塩化物によるステレオレテント伝達.
- オルガノジン製の反応剤が,電ophiles とクロスカップリング反応で,その後に反応する.
主要な成果
- 構成的に安定したキラル二次アルキル亜鉛反応剤の効率的な合成
- ディフルオロカルベンのステレオ特異的な反応が示された.
- パラジアム触媒のクロスカップリングと銅媒介のトリフローロメチル化に成功
- 機械学的および計算的研究により,伝達過程が解明されました.
結論
- オーガノボロンエステルのステレオレント伝達は,キラルなオルガノシン反応剤への信頼できる経路を提供します.
- これらの有機亜鉛化合物は,非対称な合成のための多用途な構成要素です.
- 開発された方法論は,複雑なキラル分子を作るためのツールキットを拡張します.
関連する概念動画
A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn...
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.
Borane as a reagent is very reactive, as the...
Elimination reactions of alkyl halides can yield one or more alkenes depending on the specific regiochemical and stereochemical considerations. While the regiochemistry of the reaction governs the location of the double bond in the product, the stereochemical requirements often influence the geometry.
When a substrate with two different β hydrogens undergoes an E2 elimination, the presence of a strong base can yield two regioisomeric alkenes. The more-substituted alkene is the major...
Halogenation is the addition of chlorine or bromine across the double bond in an alkene to yield a vicinal dihalide. The reaction occurs in the presence of inert and non-nucleophilic solvents, such as methylene chloride, chloroform, or carbon tetrachloride.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
A...
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.
Mechanism
The hydroboration-oxidation reaction is a two-step...
Overview
The acid-catalyzed addition of water to the double bond of alkenes is a large-scale industrial method used to synthesize low-molecular-weight alcohols. An acidic atmosphere is required to allow the hydrogen in the water molecule to act as an electrophile and attack the double bond in an alkene. The addition of a proton to the double bond creates a carbocation intermediate. The proton preferentially bonds to the less substituted end of the double bond to create a more stable carbocation...