関連する実験動画

Updated: Feb 28, 2026

A Microwave-Assisted Direct Heteroarylation of Ketones Using Transition Metal Catalysis

A Microwave-Assisted Direct Heteroarylation of Ketones Using Transition Metal Catalysis

Published on: February 16, 2020

ヘテロアーレンのC-Hアルケニル化:チオエーテルリガンドによって可能になったメカニズム,速度,および選択性変化

Bradley J Gorsline¹, Long Wang¹, Peng Ren¹

¹Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States.

Journal of the American Chemical Society

|June 17, 2017

まとめ

新しいチオエーテルリガンドは,ヘテロアーレンのパラジウム触媒化C-Hアルケニル化を劇的に加速し,より速い反応とユニークな選択性を可能にします. この画期的な発見は薬の発見と合成に有効な方法を提供します

科学分野:

有機化学
キャタリシス
薬剤化学

背景:

C-H機能化は有機合成における重要な変換である.
パラジウム触媒反応は広く使用されていますが,しばしば厳しい条件または特定の指示グループが必要です.
ヘテロアレンのC-Hアルケニル化のための効率的な触媒の開発は依然として課題です.

研究の目的:

O-, S-, N-ヘテロアレンのC-Hアルケニル化を加速する新しい補助リガンドを特定する.
観測された速度加速と選択性の背後にあるメカニズムを解明する.
薬剤の機能化後期を含む様々なヘテロアレン誘導体の合成におけるこれらのリガンドの有用性を実証する.

主な方法:

パラジウム触媒のためのチオエーテル補助リガンドの合成とスクリーニング.
反応速度を決定し,速度を制限するステップを特定するための運動研究.
同位体ラベリングと計算研究を含むメカニズム調査.
開発された触媒系をO,S,Nヘテロアーレンの範囲に適用する (55例).

主要な成果:

ティオエーテル・リガンドは,リガンドなしのシステムよりも800倍速く,パラジアム触媒によるC-Hアルケニル化を著しく加速する.
C-H 債券の分割は,売上を制限するステップとして特定されました.
リガンド協調は反応経路を中性からカチオンに変化させ,速度を高める.
阻害された位置での機能化を可能にする,触媒制御されたサイト選択性が観察されました.
軽度の反応条件と短い反応時間は,多数の基板で達成された.

結論:

チオエーテルリガンドは,ヘテロアーレンのパラジウム触媒化C-Hアルケニル化を加速するための強力なツールです.
機械的洞察は,C-H活性化を含む触媒サイクルをより深く理解します.
この方法論は,複雑な分子を合成し,薬剤の末期派生を可能にするために,多用途で効率的なアプローチを提供します.

さらに関連する動画

Catalytic Reactions at Amine-Stabilized and Ligand-Free Platinum Nanoparticles Supported on Titania During Hydrogenation of Alkenes and Aldehydes

Catalytic Reactions at Amine-Stabilized and Ligand-Free Platinum Nanoparticles Supported on Titania During Hydrogenation of Alkenes and Aldehydes

Published on: June 24, 2022

Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate

Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate

Published on: June 21, 2017

関連する概念動画

Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule

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...

Acid-Catalyzed α-Halogenation of Aldehydes and Ketones

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...

Reduction of Alkenes: Asymmetric Catalytic Hydrogenation

Reduction of Alkenes: Asymmetric Catalytic Hydrogenation

Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...

Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration

Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration

The rate of acid-catalyzed hydration of alkenes depends on the alkene's structure, as the presence of alkyl substituents at the double bond can significantly influence the rate.

Electrophilic Addition to Alkynes: Halogenation

Electrophilic Addition to Alkynes: Halogenation

Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.

α-Alkylation of Ketones via Enolate Ions

α-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...