Video Experimental Relacionado
Updated: May 3, 2026
06:46
Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
6.6K
Alquilación selectiva del sitio catalizada por níquel de enlaces C ((sp3) -H no activados
Xuesong Wu1, Yan Zhao, Haibo Ge
1Department of Chemistry and Chemical Biology, Indiana University Purdue University Indianapolis , Indianapolis, Indiana 46202 United States.
Journal of the American Chemical Society
|January 23, 2014
Resumen
La catálisis del níquel alquila directamente los enlaces C-H no activados sp(3) en las amidas alifáticas. Este método se dirige preferentemente a los grupos metilo sobre los grupos metileno, lo que demuestra una amplia tolerancia al grupo funcional para una síntesis química eficiente.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La catálisis es la catálisis.
- Metodología sintética de la metodología sintética.
Sus antecedentes:
- La funcionalización directa de los enlaces C-H no activados sp(3) sigue siendo un desafío importante en la síntesis orgánica.
- Las amidas alifáticas son motivos estructurales prevalentes en productos farmacéuticos y materiales.
- Es muy deseable desarrollar métodos selectivos y eficientes para la activación de enlaces C-H de amida.
Objetivo del estudio:
- Desarrollar un nuevo método catalizado por níquel para la alquilación directa de enlaces C-H no activados sp(3) en amidas alifáticas.
- Investigar la selectividad de la reacción hacia diferentes tipos de enlaces C-H (metilo vs. metileno) y grupos funcionales.
- Para aclarar el mecanismo de reacción, incluida la función del grupo de dirección y el paso de ciclometalización.
Principales métodos:
- Alquilación directa catalizada por níquel utilizando un grupo directivo bidentado.
- Empleando varias amidas alifáticas con diversos grupos funcionales.
- Estudios mecanicistas que involucran análisis intermedio y modelado computacional.
Principales resultados:
- Se logró una alquilación directa exitosa de enlaces C-H de amidas alifáticas no activadas sp(3).
- La reacción exhibe una fuerte preferencia por los enlaces metilo C-H sobre los enlaces metileno C-H.
- Una amplia gama de grupos funcionales fueron tolerados, destacando la robustez de la reacción.
- Las investigaciones mecánicas sugieren que un anillo intermedio de cinco miembros juega un papel clave en la dirección de la selectividad sobre los enlaces C-H de las arenas.
Conclusiones:
- Se ha establecido una nueva y eficiente alquilación directa catalizada por níquel de los enlaces C-H de las amidas alifáticas sp ((3)).
- El método ofrece una alta selectividad para los enlaces metilo C-H y una amplia compatibilidad de grupos funcionales.
- Este trabajo proporciona una nueva herramienta valiosa para la síntesis de moléculas complejas que contienen fracciones de amida funcionalizadas.
Videos de Conceptos Relacionados
02:27Preparation of Alkynes: Alkylation Reaction
9.4K
Introduction
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
9.4K
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
6.9K
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.
6.9K
02:38Electrophilic Addition to Alkynes: Halogenation
7.4K
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.
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.
7.4K
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
2.6K
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...
2.6K
01:10α-Alkylation of Ketones via Enolate Ions
2.4K
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...
2.4K
02:17Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
14.2K
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...
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...
14.2K