アルケニルインドールのパラジウム触媒によるサイクル化/カルボアルコキシル化
1P. M. Gross Chemical Laboratory, Duke University, Durham, NC 27708-0346, USA.
Journal of the American Chemical Society
|August 19, 2004
まとめ
この研究は,テトラヒドロカルバゾール合成のための新しいパラジウム触媒反応を導入しています. 効率的なサイクリング/カルボアルコキシル化方法は,穏やかな条件下で動作し,様々な機能群を許容します.
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:
- インドール誘導体は,天然製品や医薬品における重要な構造モチーフである.
- 代用カルバゾールへの効率的な合成経路は非常に求められています.
- パラジウム触媒反応は,C-CとC-ヘテロ原子結合形成のための強力なツールを提供します.
研究 の 目的:
- テトラヒドロカルバゾールの合成のための新しいパラジウム触媒法を開発する.
- サイクル化/カルボアルコキシル化反応の範囲と限界を調査する.
- 様々なインドル基板に対するこの方法の有用性を探求する.
主な方法:
- CO大気下でのメタノール中の2-(4-ペンテニル) インドールと触媒PdCl2(CH3CN) 2とステキオメトリックCuCl2の反応.
- 触媒の負荷,温度,反応時間を含む反応条件の最適化.
- アルケニル鎖の長さと置換パターンの変動を含む基板の範囲の分析.
主要な成果:
- テトラヒドロカルバゾール誘導体の合成が成功し,単一のレジオアイゾーマーとして83%の収量を得ました.
- パラジアム触媒によるサイクリング/カルボアルコキシル化は,アルケニル鎖の置換に対する耐性を示した.
- この反応は,異なるアルケニル鎖長と結合位置を持つものを含む,様々なインドール誘導体に対して効果的であった.
結論:
- テトラヒドロカルバゾール合成のための新しい効率的なパラジウム触媒サイクリング/カルボアルコキシル反応が確立されました.
- この方法は汎用性があり,さまざまな機能群と基板のバリエーションを許容します.
- これは,複雑なインドルを含む分子にアクセスするための貴重な新しいツールを提供します.
関連する概念動画
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.
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.
Reduction 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.
Reactions 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...
Acid-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...
Alkenes via Reductive Coupling of Aldehydes or Ketones: McMurry Reaction
The radical dimerization of ketones or aldehydes gives vicinal diols through a pinacol coupling reaction. However, the behavior of titanium metals used for the reaction as a source of electrons is unusual. When the reaction is carried out in the presence of titanium, diols can be isolated at low temperatures. Else titanium further reacts with diols, forming alkenes through the McMurry reaction.
Acid-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.


