関連する実験動画

Updated: Jan 21, 2026

A Direct, Regioselective and Atom-Economical Synthesis of 3-Aroyl-N-hydroxy-5-nitroindoles by Cycloaddition of 4-Nitronitrosobenzene with Alkynones

A Direct, Regioselective and Atom-Economical Synthesis of 3-Aroyl-N-hydroxy-5-nitroindoles by Cycloaddition of 4-Nitronitrosobenzene with Alkynones

Published on: January 21, 2020

オキシアリル/ダイエン (3+2) サイクル添加物から5ビニル-2-メチレンフランの選択的形成の起源 Pd(0) 触媒

Yike Zou¹, Shuming Chen¹, K N Houk¹

¹Department of Chemistry and Biochemistry , University of California , Los Angeles , California 90095-1569 , United States.

Journal of the American Chemical Society

|July 23, 2019

まとめ

この研究は,結合ダイエンの電子欠乏性パラジアム-オキシアリル (Pd-oxyallyl) サイクル添加が段階的なメカニズムで進行することを明らかにしています. 計算分析は,C−C結合形成を促進するエステル置換剤の役割を強調する.

科学分野:

有機金属化学
有機合成
コンピュータ化学

背景:

パラジウム触媒によるサイクル添加は有機合成において極めて重要です.
合成経路の最適化には反応メカニズムを理解することが重要です

研究の目的:

電子欠乏のPd-オキシアリルと結合ダイエンの間の (3+2) サイクロアディションのメカニズムを調査する.
反応性や選択性に影響する要因を明らかにする.

主な方法:

密度関数理論 (DFT) の計算を用いた.
反応経路,移行状態,および電子特性の分析.

主要な成果:

初期C-C結合形成の段階的なメカニズムが計算的にサポートされています.
電子を取り除くエステル置換剤は,LUMOエネルギーを低下させ,移動挿入障壁を軽減します.
モノエンの反応は,より高い挿入障壁とC-O除去障壁のために不利である.
結合ダイエンは,電愛性 η3 Pd-アルリル種とC-O結合の形成を促進する.

結論:

この研究は,Pd-オキシアリルサイクル添加物の詳細なメカニズムの洞察を提供します.
エステル置換剤とダイエンの結合は,効率的なサイクル添加反応に不可欠である.
DFT計算は,有機金属触媒の反応性を予測し理解するのに価値があります.

さらに関連する動画

In Vivo 2-Photon Calcium Imaging in Layer 2/3 of Mice

In Vivo 2-Photon Calcium Imaging in Layer 2/3 of Mice

Published on: March 13, 2008

Multiplexed Immunofluorescence Analysis and Quantification of Intratumoral PD-1+ Tim-3+ CD8+ T Cells

Multiplexed Immunofluorescence Analysis and Quantification of Intratumoral PD-1+ Tim-3+ CD8+ T Cells

Published on: February 8, 2018

関連する概念動画

[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction

[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction

The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.

ortho–para-Directing Activators: –CH3, –OH, –&NoBreak;NH2, –OCH3

ortho–para-Directing Activators: –CH₃, –OH, –⁠NH₂, –OCH₃

All ortho–para directors, excluding halogens, are activating groups. These groups donate electrons to the ring, making the ring carbons electron-rich. Consequently, the reactivity of the aromatic ring towards electrophilic substitution increases. For instance, the nitration of anisole is about 10,000 times faster than the nitration of benzene. The electron-donating effect of the methoxy group in anisole activates the ortho and para positions on the ring and stabilizes the corresponding...

Catalysis

Catalysis

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.

meta-Directing Deactivators: –NO2, –CN, –CHO, –&NoBreak;CO2R, –COR, –CO2H

meta-Directing Deactivators: –NO₂, –CN, –CHO, –⁠CO₂R, –COR, –CO₂H

All meta-directing substituents are deactivating groups. These substituents withdraw electrons from the aromatic ring, making the ring less reactive toward electrophilic substitution. For example, the nitration of nitrobenzene is 100,000 times slower than that of benzene because of the deactivating effect of the nitro group. The first step in an electrophilic aromatic substitution is the addition of an electrophile to form a resonance-stabilized carbocation. The energy diagrams for...

2° Amines to N-Nitrosamines: Reaction with NaNO2

2° Amines to N-Nitrosamines: Reaction with NaNO₂

Secondary amines react with nitrous acid to form N-nitrosamines, as depicted in Figure 1. Nitrous acid, a weak and unstable acid, is formed in situ from an aqueous solution of sodium nitrite and strong acids, such as hydrochloric acid or sulfuric acid, in cold conditions. In the presence of an acid, the nitrous acid gets protonated. The subsequent loss of water results in the formation of the electrophile known as nitrosonium ion.

SN2 Reaction: Kinetics

S_N2 Reaction: Kinetics

Kinetic Studies and Significance
In a chemical reaction, a relationship exists between the concentration of reactants and the rate at which the reaction proceeds. The study to measure this relationship is known as the kinetics of a chemical reaction. Kinetic studies are used to deduce the rate law of a chemical reaction, which provides information about the species involved during the transition state of the rate-determining step. Thus, kinetic studies help to derive the mechanism of a...