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Regioselectivity and Stereochemistry of Hydroboration02:36

Regioselectivity 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-Oxidation of Alkenes03:08

Hydroboration-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.
Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation02:47

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.
Preparation of Alcohols via Addition Reactions02:15

Preparation of Alcohols via Addition Reactions

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...
Radical Anti-Markovnikov Addition to Alkenes: Mechanism01:17

Radical Anti-Markovnikov Addition to Alkenes: Mechanism

The reaction of hydrogen bromide with alkenes in the presence of hydroperoxides or peroxides proceeds via anti-Markovnikov addition. The radical chain reaction comprises initiation, propagation, and termination steps.
The mechanism starts with chain initiation, which involves two steps. In the first chain initiation step, a weak peroxide bond is homolytically cleaved upon mild heating to form two alkoxy radicals. In the second initiation step, a hydrogen atom is abstracted by the alkoxy radical...
Regioselectivity of Electrophilic Additions-Peroxide Effect02:35

Regioselectivity of Electrophilic Additions-Peroxide Effect

In the presence of organic peroxides, the addition of hydrogen bromide to an alkene yields the isomer that is not predicted by Markovnikov’s rule. For example, the addition of hydrogen bromide to 2-methylpropene in the presence of peroxides gives 1-bromo-2-methylpropane. This addition reaction proceeds via a free radical mechanism, which reverses the regioselectivity. The free radical reaction mechanism involves three stages: initiation, propagation, and termination.

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関連する実験動画

Updated: Jul 4, 2026

Synthesis of a Borylated Ibuprofen Derivative Through Suzuki Cross-Coupling and Alkene Boracarboxylation Reactions
08:56

Synthesis of a Borylated Ibuprofen Derivative Through Suzuki Cross-Coupling and Alkene Boracarboxylation Reactions

Published on: November 30, 2022

酸素を誘導した分子内水溶解法.

Robert-André F Rarig1, Matthew Scheideman, Edwin Vedejs

  • 1Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA.

Journal of the American Chemical Society
|June 25, 2008
PubMed
まとめ
この要約は機械生成です。

この研究では,同性アルコールに対する金属無性内分子水酸化法が導入されました. このプロセスは,C5の分岐によって強化された1,3-二酸化炭素置換製品の高い地域選択性を達成します.

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Synthesis of Antiviral Tetrahydrocarbazole Derivatives by Photochemical and Acid-catalyzed C-H Functionalization via Intermediate Peroxides (CHIPS)
06:34

Synthesis of Antiviral Tetrahydrocarbazole Derivatives by Photochemical and Acid-catalyzed C-H Functionalization via Intermediate Peroxides (CHIPS)

Published on: June 20, 2014

Versatile CO2 Transformations into Complex Products: A One-pot Two-step Strategy
07:36

Versatile CO2 Transformations into Complex Products: A One-pot Two-step Strategy

Published on: November 9, 2019

関連する実験動画

Last Updated: Jul 4, 2026

Synthesis of a Borylated Ibuprofen Derivative Through Suzuki Cross-Coupling and Alkene Boracarboxylation Reactions
08:56

Synthesis of a Borylated Ibuprofen Derivative Through Suzuki Cross-Coupling and Alkene Boracarboxylation Reactions

Published on: November 30, 2022

Synthesis of Antiviral Tetrahydrocarbazole Derivatives by Photochemical and Acid-catalyzed C-H Functionalization via Intermediate Peroxides (CHIPS)
06:34

Synthesis of Antiviral Tetrahydrocarbazole Derivatives by Photochemical and Acid-catalyzed C-H Functionalization via Intermediate Peroxides (CHIPS)

Published on: June 20, 2014

Versatile CO2 Transformations into Complex Products: A One-pot Two-step Strategy
07:36

Versatile CO2 Transformations into Complex Products: A One-pot Two-step Strategy

Published on: November 9, 2019

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
  • カタリシス カタリシス カタリシス

背景:

  • 分子内ヒドロボレーションは,重要な合成変換である.
  • 金属のない触媒システムの開発は,有機合成の重要な目標です.
  • グループ戦略を指揮することは,地域選択性をコントロールするために極めて重要です.

研究 の 目的:

  • 新しい金属のないホモアリル酸性酸素誘導の分子内水酸化を報告する.
  • ホモアリルアルコールの水酸化で高い地域選択性を達成する.
  • 領域選択性に対する基板分岐の影響を調査する.

主な方法:

  • ディメチル硫化ボラン (Me2S.BH3) とトリフリック酸 (TfOH) を採用した金属のないシステムを使用しました.
  • ホモアリルアルコールの酸素誘導型分子内水酸化を用いた.
  • 標準的な酸化処理を行い,最終製品を得る.

主要な成果:

  • 20:1から82:1までの高い地域選択性を達成した.
  • 1,3-二酸化炭素置換製品の形成に強い好みを示した.
  • 基板のC5位置での分岐が,地域選択性を著しく改善することを観察した.

結論:

  • 開発された方法は,有価な酸化有機化合物への効率的で選択的な経路を提供します.
  • この金属のないアプローチは,伝統的な水力掘削方法のよりグリーンな代替手段を提供します.
  • C5分岐のような基質構造的改変は,反応結果を高めるために戦略的に使用することができます.