ニッケルから二金属C-C結合形成の還元性除去
Hongwei Xu1, Justin B Diccianni1, Joseph Katigbak1
1Department of Chemistry, New York University , 100 Washington Square East, New York, New York 10003, United States.
Journal of the American Chemical Society
|March 24, 2016
まとめ
この研究では,ニッケル触媒によるクロスカップリング反応における二分子還元除去が直接観察されました. sp(3) -sp(3) エタンの形成とsp(2) -sp(2) ビフェニルの形成の異なる経路が特定され,重要な反応メカニズムが明らかにされた.
科学分野:
- 有機金属化学
- キャタリシス
- 有機合成
背景:
- ニッケル触媒によるクロスカップリング反応は有機合成において不可欠である.
- 削減的な排除のような重要なステップを特徴づけるのは困難です.
- 双分子経路は提案されたが,実験的な支持は得られなかった.
研究 の 目的:
- ニッケル触媒における二分子還元性除去を直接観察し,特徴づけること.
- sp(3) -sp(3) とsp(2) -sp(2) のC−C結合形成の異なるメカニズムを解明する.
- 提案された二分子経路の実験的証拠を提供するために.
主な方法:
- 明確に定義された (ピリジン-ピロリル) Ni モノメチルおよびモノフェニル複合体の製造
- 還元性排除反応の直接観察
- 酸化物質とドナーリガンドを含む運動研究
主要な成果:
- 双分子還元性除去によるエタン (sp(3) -sp(3) とビフェニル (sp(2) の直接観察.
- 酸化剤によって促進されるNi (III) 二酸化は,メチルとエタンの結合の鍵となる.
- ビデント酸リガンドの協調はビフェニル形成を促進する.
結論:
- この研究は,ニッケル触媒における二分子還元性除去の直接的な実験的証拠を提供します.
- 異なる機械的経路は,sp(3) -sp(3) とsp(2) -sp(2) カップリングで動作します.
- これらの経路を理解することで,クロスカップリング反応の設計と効率が向上します.
関連する概念動画
Catalysis
32.1K
The presence of a catalyst affects the rate of a chemical reaction. A catalyst is a substance that can increase the reaction rate without being consumed during the process. A basic comprehension of a catalysts’ role during chemical reactions can be understood from the concept of reaction mechanisms and energy diagrams.
32.1K
Nitriles to Amines: LiAlH4 Reduction
5.0K
Nitriles are reduced to amines in the presence of strong reducing agents like lithium aluminum hydride through a typical nucleophilic acyl substitution. The reaction requires two equivalents of the reducing agent. The reducing agent acts as a source of hydride ions.
As shown below, the mechanism involves three steps. Firstly, the hydride ion acting as a nucleophile attacks the nitrile carbon to form an anion. In the second step, a second equivalent of the hydride ion attacks the anion to...
As shown below, the mechanism involves three steps. Firstly, the hydride ion acting as a nucleophile attacks the nitrile carbon to form an anion. In the second step, a second equivalent of the hydride ion attacks the anion to...
5.0K
Acid Halides to Ketones: Gilman Reagent
4.3K
Lithium dialkyl cuprate, also known as Gilman reagents, selectively reduces acid halides to ketones. The acid chloride is treated with Gilman reagent at −78 °C in the presence of ether solution to produce a ketone in good yield.
As shown below, the mechanism proceeds in two steps. First, one of the alkyl groups of the reagent acts as a nucleophile and attacks the acyl carbon of the acid chloride to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen...
As shown below, the mechanism proceeds in two steps. First, one of the alkyl groups of the reagent acts as a nucleophile and attacks the acyl carbon of the acid chloride to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen...
4.3K
Elimination Reactions
18.5K
A nucleophile can react with an alkyl halide to give the substitution product by displacing the halogen. Or it can function as a base to give the elimination product by deprotonation of the neighboring carbon to form an alkene. In an elimination reaction, the substrate loses two groups from adjacent carbons forming at least one π bond. The carbon attached to the halogen is called the α carbon, while the adjacent carbon is called the β carbon; hence, these reactions are called...
18.5K
Benzene to 1,4-Cyclohexadiene: Birch Reduction Mechanism
2.8K
Birch reduction uses solvated electrons as reducing agents. The reaction converts benzene to 1,4-cyclohexadiene. The reaction proceeds by the transfer of a single electron to the ring to form a benzene radical anion. This anion is highly basic—it abstracts a proton from the alcohol to form a cyclohexadienyl radical. Another single electron transfer gives the cyclohexadienyl anion. A proton transfer from the alcohol forms 1,4-cyclohexadiene. Since this reduction occurs via radical anion...
2.8K
Preparation of Aldehydes and Ketones from Nitriles and Carboxylic Acids
4.7K
Although it is possible to reduce a carboxylic acid to an aldehyde, strong reducing agents, like lithium aluminum hydride (LAH), prohibit a controlled reduction, instead causing the generated aldehyde to instantly over-reduce to a primary alcohol.
Reducing carboxylic acid derivatives like acyl chlorides (RCOCl), esters (RCO2R′), and nitriles (RCN) using milder aluminum hydride agents like lithium tri-tert-butoxyaluminum hydride [LiAlH(O-t-Bu)3] and diisobutylaluminum hydride [DIBAL-H]...
Reducing carboxylic acid derivatives like acyl chlorides (RCOCl), esters (RCO2R′), and nitriles (RCN) using milder aluminum hydride agents like lithium tri-tert-butoxyaluminum hydride [LiAlH(O-t-Bu)3] and diisobutylaluminum hydride [DIBAL-H]...
4.7K


