カーボニルアニオンの触媒結合添加は,中性水性条件下で加えられる
Michael C Myers1, Ashwin R Bharadwaj, Benjamin C Milgram
1Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA.
Journal of the American Chemical Society
|October 20, 2005
まとめ
シアゾリウム塩の触媒は,中性水中の条件下でカルボニルアニオンの結合添加を可能にします. この効率的な方法は二酸化を回避し,さらなる合成のために1,4-ジカルボニル化合物を生成します.
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
- グリーン・ケミストリー (Green Chemistry)
背景:
- シアゾリウム塩は,有機合成における効果的な触媒である.
- ニュートラルな水分条件下での触媒方法の開発は,持続可能な化学にとって極めて重要です.
研究 の 目的:
- シアゾリウム塩の触媒を用いてカルボニルアニオンの結合添加を達成する.
- 反応を中性水性条件下で実行する.
- 1,4-ジカルボニル化合物を合成するために.
主な方法:
- アルファ-ケトカルボキシラートとチアゾリウム由来ズウィッテリオンを使用して,カルボニルアニオンを生成します.
- 代替アルファ,ベータ不飽和-2-アシルイミダゾールを電友として使用した.
- シアゾリウム塩5を用いた反応条件の最適化,これはチアミン二酸化塩酸の類型である.
主要な成果:
- カーボニルアニオンの結合添加を中性水性条件下で成功的に触媒化しました.
- 様々なアルファ-ケトカルボキシラートおよびβ-アリル置換の不飽和の2-アシルイミダゾールによる広範な基板範囲が実証されています.
- 効率的なカルボニルアニオン利用を示すベンゾイン製品形成は観察されなかった.
- N-メチリミダゾール活性化による1,4-ジカルボニル産物のエステルおよびアミドへの効率的な変換を達成しました.
結論:
- 水中の新しく効率的なチアゾリウム触媒結合添加反応を開発した.
- この方法は,価値ある1,4-ジカルボニル化合物を合成するためのよりグリーンな代替案を提供します.
- 反応の範囲と,その後の機能化は,その合成的有用性を示しています.
関連する概念動画
01:18Nucleophilic Addition to the Carbonyl Group: General Mechanism
The carbonyl carbon in an aldehyde or ketone is the site of a nucleophilic attack due to its electron-deficient nature. Depending on the strength of the incoming nucleophile, the reaction occurs via different mechanistic pathways.
A stronger nucleophile can directly attack the electrophilic center, the carbonyl carbon. The HOMO orbital of the nucleophile interacts with the LUMO (π* antibonding) orbital present on the carbonyl carbon. This interaction breaks the π bond and shifts the π bonding...
A stronger nucleophile can directly attack the electrophilic center, the carbonyl carbon. The HOMO orbital of the nucleophile interacts with the LUMO (π* antibonding) orbital present on the carbonyl carbon. This interaction breaks the π bond and shifts the π bonding...
01:08Base-Catalyzed Aldol Addition Reaction
As depicted in Figure 1, base-catalyzed aldol addition involves adding two carbonyl compounds in aqueous sodium hydroxide to form a β-hydroxy carbonyl compound.
01:09Conjugate 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.
01:08Conjugate Addition of Enolates: Michael Addition
The attack of a nucleophile at the β carbon of an α,β-unsaturated carbonyl compound is called conjugate addition. Conjugate addition reactions of active methylene compounds, such as β-diketones, β-keto esters, β-keto nitriles, and α-nitro ketones, are called Michael addition reactions.
01:15Acid-Catalyzed Aldol Addition Reaction
The aldol reaction of a ketone under acidic conditions successfully forms an unsaturated carbonyl as the final product instead of an aldol. The acid-catalyzed aldol reaction is depicted in Figure 1.
01:27Conjugate Addition (1,4-Addition) vs Direct Addition (1,2-Addition)
α,β-Unsaturated carbonyl compounds with two electrophilic sites, the carbonyl carbon, and the β carbon, are susceptible to nucleophilic attack via two modes: conjugate or 1,4-addition and direct or 1,2-addition.
Conjugate addition results in a thermodynamically stable product. The reaction retains the stronger C=O bond at the expense of the weaker C=C π bond. The process is slow as the β carbon is less electrophilic than the carbonyl carbon.
Direct addition products are formed faster owing to...
Conjugate addition results in a thermodynamically stable product. The reaction retains the stronger C=O bond at the expense of the weaker C=C π bond. The process is slow as the β carbon is less electrophilic than the carbonyl carbon.
Direct addition products are formed faster owing to...