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Updated: May 15, 2026
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Chemoselective Modification of Viral Surfaces via Bioorthogonal Click Chemistry
Published on: August 19, 2012
アリファティックアルデヒドのエナチオセレクティブホモクロチルボレーション
Hongkun Lin1, Wenbo Pei, Hao Wang
1Department of Chemistry, Brandeis University, Waltham, Massachusetts 02454-9110, United States.
Journal of the American Chemical Society
|December 22, 2012
まとめ
この研究は,光学的に純粋なシンホモクロティレーション反応剤を作成するための実用的な方法を提示し,貴重な有機化合物の高度な選択的合成を可能にします.
科学分野:
- 有機化学 オーガニック・ケミストリー
- アシンメトリック・シンセシス
- オルガノボロン化学 オルガノボロン化学
背景:
- ステレオ選択合成のための効率的な方法の開発は,有機化学において極めて重要です.
- シン-ホモクロチレーション反応は,複雑な分子を構成するために重要です.
- ダイアステレオ選択性とエナチオ選択性の両方を制御することは,依然として課題です.
研究 の 目的:
- 光学的に純粋なシンホモクロティレーション反応剤を合成するための実用的で高度に選択的な経路を確立する.
- ボロンベースの反応剤を用いたシンホモクロティレーションのメカニズムを調査する.
- さまざまなシンホモクロチル製品を調製し,特徴づけること.
主な方法:
- ホモクロティレーションの活性化剤としてフェニルボロン二塩化物 (PhBCl2) を利用した.
- 反応中間物質を特定するために,核磁共振 (NMR) スペクトロスコーピーを用いた.
- 反応機構と移行状態を明らかにするために計算研究を実施した.
主要な成果:
- 多数のシンホモクロチル産物の高度にダイアステレオ選択的およびエナチオ選択的調製を達成した.
- サイクロプロピルカルビニルジクロロボランを活性型ホモクロティライティング種として特定した.
- NMR実験と計算学的研究は,クロロボラン中介物質とジマーマン-トラックスラー移行状態を含む提案された反応機構を支持した.
結論:
- 開発された方法は,光学的に純粋なシンホモクロチレーション反応剤への実用的な経路を提供します.
- この研究は,ボロン化合物によって媒介されるステレオセレクティブのホモアリル/ホモクロチル移転のメカニズムを明らかにしています.
- この研究は,キラルな有機分子合成のための貴重な洞察を提供します.
関連する概念動画
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.
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...
02:44Oxidation 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.
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
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...
02:36Regioselectivity and Stereochemistry of Hydroboration
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 stereochemistry.
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 stereochemistry.