Video Experimental Relacionado

Updated: Dec 3, 2025

Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions

Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions

Published on: July 30, 2017

Control de aniones espaciales en el paladio para la arilación C-H leve de arenas

Jyoti Dhankhar¹, Elisa González-Fernández¹, Chao-Chen Dong¹

¹Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.

Journal of the American Chemical Society

|October 30, 2020

Resumen

Los investigadores desarrollaron un control espacial de aniones para la arilación directa C-H de las arenas. Este método funciona a temperatura ambiente, lo que permite la diversificación de las moléculas en las últimas etapas en condiciones suaves.

Área de la Ciencia:

Química orgánica
Catálisis

Sus antecedentes:

La arilación directa C-H de arenas sin grupos directos es difícil.
La funcionalización del benceno sigue siendo un desafío importante en la síntesis orgánica.

Objetivo del estudio:

Introducir el control espacial de aniones para el diseño de sitios catalíticos.
Para permitir la arilación no dirigida de C-H de arenas en condiciones suaves.

Principales métodos:

Desarrollo de un sistema catalítico que utiliza el control espacial de aniones.
Aplicación del método para la activación del enlace C-H a temperatura ambiente.

Principales resultados:

Se obtiene una arilación C-H no dirigida de las arenas a temperatura ambiente.
Se ha demostrado la diversificación estructural en etapa tardía de pequeñas moléculas biológicamente relevantes.
Se obtiene una selectividad del emplazamiento complementaria de los métodos de funcionalización existentes.

Conclusiones:

El control espacial de aniones es una estrategia prometedora para la catálisis de metales de transición.
Este enfoque facilita la funcionalización del enlace C-H en condiciones suaves.
El método ofrece nuevas posibilidades para sintetizar moléculas orgánicas complejas.

Más Videos Relacionados

Achieving Moderate Pressures in Sealed Vessels Using Dry Ice As a Solid CO2 Source

Achieving Moderate Pressures in Sealed Vessels Using Dry Ice As a Solid CO2 Source

Published on: August 17, 2018

Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-phosphinetriyltripiperidine]}palladium Under Mild Reaction Conditions

Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-phosphinetriyltripiperidine]}palladium Under Mild Reaction Conditions

Published on: March 20, 2014

Videos de Conceptos Relacionados

π Molecular Orbitals of the Allyl Cation and Anion

π Molecular Orbitals of the Allyl Cation and Anion

An allyl group is a three-carbon conjugated system where the sp³-hybridized allylic carbon is bonded to a CH=CH2 group via a single bond. Allyl anions can be obtained by treating propene with a strong base that can deprotonate methyl groups. Allyl cations are formed as intermediates during substitution reactions involving allylic halides. In both cases, the hybridization of the allylic carbon changes from sp3 to sp2, giving rise to a carbon chain with three sp2-hybridized carbons, each with...

Aromatic Hydrocarbon Anions: Structural Overview

Aromatic Hydrocarbon Anions: Structural Overview

Neutral hydrocarbons like cyclopentadiene with an odd number of carbon atoms and one intervening CH2 group in the ring are not aromatic. Cyclopentadiene with 4 π electrons does not satisfy the 4n + 2 π electron rule. Additionally, the intervening CH2 group is sp3 hybridized and lacks a vacant p orbital, thereby interrupting the overlap of p orbitals in a continuous manner and preventing the delocalization of π electrons throughout the ring.
Due to the absence of continuous...

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...

Diazonium Group Substitution: –OH and –H

Diazonium Group Substitution: –OH and –H

Nitrous acid, a weak acid, is prepared in situ via the reaction of sodium nitrite with a strong acid under cold conditions. This nitrous acid prepared in situ reacts with primary arylamines to form arenediazonium salts. Such reactions are known as diazotization reactions. As shown in Figure 1, the formation of arenediazonium salts begins with the decomposition of nitrous acid in an acidic solution to give nitrosonium ions.

Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic SN1

Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic S_N1

Treating arylamines with nitrous acid gives aryldiazonium salts that are effective substrates in nucleophilic aromatic substitution reactions. The diazonio group in these salts can be easily displaced by different nucleophiles, yielding a wide variety of substituted benzenes. The leaving group departs as nitrogen gas, and this easy elimination is the driving force for the substitution reaction.
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo,...

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...