ステレオ選択的有機反応:カルボニル添加プロセスの触媒
1Department of Chemistry, Harvard University, Cambridge, MA 02138.
まとめ
研究者は,ステレオ選択的有機反応のためのキラル触媒を開発しています. このレビューは,カーボニルにヌクレオフィルをエナチオセレクティブで添加する触媒に焦点を当て,ステレオ差別化に関するメカニズム的な洞察を提供しています.
科学分野:
- 有機化学 オーガニック・ケミストリー
- カタリシス カタリシス カタリシス
- ステレオ化学 ステレオ化学
背景:
- ステレオ選択的有機反応の重要な進歩.
- チラルの触媒は,重要な新興研究方向である.
- カーボニルへのエナチオセレクティブ・ヌクレオフィリック添加にフォーカスする.
研究 の 目的:
- カルボニル基板にエナンチオセレクティブ・ヌクレオフィリック添加のための触媒および触媒モデルの開発をレビューする.
- キラル触媒のこの特定の領域における現在の理解を統一する.
- ステレオ差別化移行状態に関するメカニズム的洞察を提供すること.
主な方法:
- エナチオセレクティブ反応のためのキラル触媒の文献レビュー.
- ステレオ差別化のメカニズムモデルの分析.
- カルボニルへのヒドリドと炭素核フィルの添加にフォーカスする.
主要な成果:
- キラル触媒の開発における最近の進歩をまとめました.
- ステレオ選択的移行状態のためのメカニズム構造のプレゼンテーション.
- エナチオセレクティブの核性添加物のための触媒開発の統一.
結論:
- チラルの触媒は,ステレオ選択的有機合成を進めるために極めて重要です.
- 移行状態のメカニズムを理解することは,効果的な触媒の設計の鍵です.
- このレビューは,エナチオセレクティブカルボニル添加物の触媒に関する知識を統合しています.
関連する概念動画
Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
If a set of reactants can yield multiple constitutional isomers, but one of the isomers is obtained as the major product, the reaction is said to be regioselective. In such reactions, bond formation or breaking is favored at one reaction site over others.
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
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.
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 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.
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...
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...
Conjugate Addition to α,β-Unsaturated Carbonyl Compounds
α,β-Unsaturated carbonyl compounds are molecules bearing a carbonyl and alkene functionality in conjugation with each other. The conjugation in the molecule leads to three resonance structures. The hybrid form exhibits two probable electrophilic sites: the carbonyl carbon and the β carbon.
Radical Anti-Markovnikov Addition to Alkenes: Overview
The addition of hydrogen bromide to alkenes in the presence of hydroperoxides or peroxides proceeds via an anti-Markovnikov pathway and yields alkyl bromides.


