Video Experimental Relacionado
Updated: Jun 24, 2026
![[(DPEPhos)(bcp)Cu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F59739.jpg&w=3840&q=50)
09:12
[(DPEPhos)(bcp)Cu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst
Published on: May 21, 2019
La olefinación catalizada por Pd (II) de arenas con déficit de electrones utilizando ligandos de 2,6-dialquilpiridina
Yang-Hui Zhang1, Bing-Feng Shi, Jin-Quan Yu
1Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
Journal of the American Chemical Society
|March 20, 2009
Resumen
La metaolefinación catalizada por paladio (II) de arenas con déficit de electrones se logró utilizando un nuevo ligando mutuamente repulsivo. Este método permite la síntesis de arenas 1,2,4-trisubstituidas valiosas a través de la funcionalización C-H combinada dirigida y no dirigida.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La catálisis de la catálisis.
- Metodología sintética de la metodología sintética.
Sus antecedentes:
- La funcionalización C-H es una estrategia clave en la síntesis orgánica.
- La síntesis de arenes 1,2,4-trisubstituidos sigue siendo un desafío, particularmente con sustratos con déficit de electrones.
- La catálisis de paladio ofrece potentes herramientas para la activación y la funcionalización de C-H.
Objetivo del estudio:
- Desarrollar una nueva metaolefinación catalizada por el paladio de arenas con déficit de electrones.
- Introducir un ligando racionalmente diseñado y mutuamente repulsivo para mejorar la reactividad y la selectividad.
- Establecer una vía sintética versátil para las arenas 1,2,4-trisubstituidas.
Principales métodos:
- Utilizando un sistema de catalizador de paladio (II).
- Empleando un ligando mutuamente repulsivo específicamente diseñado.
- Combinando estrategias de funcionalización C-H dirigidas y no dirigidas.
- Arenas altamente deficientes en electrones que reaccionan con las olefinas.
Principales resultados:
- Se logró una metaolefinación exitosa de arenas altamente deficientes en electrones.
- El ligando diseñado resultó crucial para la eficiencia de la reacción.
- La metodología proporciona acceso a una gama de productos de areno 1,2,4-trisubstituido.
- Se demostró una vía de funcionalización C-H dirigida y no dirigida combinada.
Conclusiones:
- Se ha desarrollado una nueva y eficiente metaolefinación catalizada por Pd (II) de arenas con déficit de electrones.
- El uso de un ligando mutuamente repulsivo es clave para esta transformación.
- Este trabajo ofrece una ruta versátil para la síntesis de valiosos 1,2,4-trisubstituidos arenes.
Videos de Conceptos Relacionados
02:17Reduction 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...
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...
02:24Reduction 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.
01:10α-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 strong interaction...
02:44Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
Alkenes are converted to 1,2-diols or glycols through a process called dihydroxylation. It involves the addition of two hydroxyl groups across the double bond with two different stereochemical approaches, namely anti and syn. Dihydroxylation using osmium tetroxide progresses with syn stereochemistry.
01:17Thermal Electrocyclic Reactions: Stereochemistry
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
01:11ortho–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...