室温でのインドルによるβ-ケトエステルのパラジウム触媒による脱水素化β'-機能化
Mikko V Leskinen1, Kai-Tai Yip, Arto Valkonen
1Department of Chemistry and NanoScience Center, University of Jyväskylä, FI-40014 JYU, Finland.
Journal of the American Chemical Society
|March 20, 2012
まとめ
この研究は,β-ケトエステルをインドールで機能させるための新しいパラジウム触媒反応を導入しています. この方法は,温和な条件下でも高い選択性と良好な収穫を達成し,新しい合成経路を提供します.
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
- 合成方法論 合成方法論
背景:
- ベータ・ケトエステルとインドールは,医薬品や材料における重要な構造モチーフです.
- それらの直接的機能化のための効率的な方法は,合成化学にとって極めて重要です.
- 既存の方法は,しばしば厳しい条件を必要とし,地域選択性が欠けている.
研究 の 目的:
- アルファ置換β-ケトエステルとインドールとの間で新しい脱水性クロスカップリング反応を開発する.
- 両カップリングパートナーにとって高い地域選択性を達成する.
- パラジウム触媒を用いて軽度の反応条件を確立する.
主な方法:
- パラジウム触媒による脱水酸化結合.
- アルファ置換β-ケトエステルとインドルを基板として利用した.
- 室温で温和な条件下で様々な酸化物質を使用した.
主要な成果:
- インドル成分に対して高いC3領域選択性を達成した.
- ベータ-ケトエステル成分に対する高いベータ'-地域選択性が実証されています.
- 温和で室温の条件下で,様々な酸化物質を用いて,良質な製品の収穫が得られる.
結論:
- 開発された方法は,機能化されたインドルおよびβ-ケトエステル誘導体の合成のための効率的で選択的な経路を提供します.
- 反応は軽度のパラジウム触媒で進行し,複雑な分子合成に魅力的です.
- インドル関与のタイミングによって異なる2つの潜在的な反応メカニズムが提案されました.
関連する概念動画
01:27Aldol Condensation with β-Diesters: Knoevenagel Condensation
The Knoevenagel condensation is an aldol-type reaction involving the condensation of aldehydes or ketones with active methylene compounds such as β-diesters to produce substituted olefins.
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...
01:13Intramolecular Claisen Condensation of Dicarboxylic Esters: Dieckmann Cyclization
Dieckmann cyclization is an intramolecular Claisen condensation of diesters. The reaction occurs in the presence of a base and generates a cyclic β-ketoester as the final product. Commonly, 1, 6 and 1, 7-diesters are preferred substrates for the reaction since the generated five, and six-membered cyclic β-keto esters are particularly more stable.
01:10α-Alkylation of Ketones via Enolate Ions
Ketones with α protons are deprotonated by strong bases like lithium diisopropylamide (LDA) to form enolate ions. The anion is stabilized by resonance, and its hybrid structure exhibits negative charges on the carbonyl oxygen and the α carbon. This ambident nucleophile can attack an electrophile via two possible sites: the carbonyl oxygen, known as O-attack, or the α carbon, known as C-attack. The nucleophilic attack via the carbanionic site is preferred. This is due to the strong interaction...
01:57Preparation of Diols and Pinacol Rearrangement
Compounds bearing two hydroxyl groups are known as diols. When the hydroxyl groups are located on adjacent carbon atoms, the diols are called vicinal diols or glycols. Under acidic conditions, vicinal diols undergo a specific reaction called pinacol rearrangement.
The reaction begins with transferring a proton from the acid catalyst to one of the hydroxyl groups, producing an oxonium ion.
The reaction begins with transferring a proton from the acid catalyst to one of the hydroxyl groups, producing an oxonium ion.
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.