Video Experimental Relacionado
Updated: Mar 14, 2026
12:08
Catalytic Reactions at Amine-Stabilized and Ligand-Free Platinum Nanoparticles Supported on Titania During Hydrogenation of Alkenes and Aldehydes
Published on: June 24, 2022
4.2K
Funcionalización hidrocarbónica catalítica y regioselectiva de alquenos no activados con varios nucleófilos C-H
Kin S Yang1, John A Gurak1, Zhen Liu1
1Department of Chemistry, The Scripps Research Institute , 10550 N. Torrey Pines Rd., La Jolla, California 92037, United States.
Journal of the American Chemical Society
|October 7, 2016
Resumen
Este estudio introduce una nueva reacción catalizada por el paladio para formar enlaces carbono-carbono utilizando alquenos y enlaces carbono-hidrógeno. Este método expande la reactividad de tipo Michael a alquenos no activados, ayudando al descubrimiento y síntesis de fármacos.
Área de la Ciencia:
- Química orgánica
- Catálisis
- Metodología sintética
Sus antecedentes:
- La formación de enlaces carbono-carbono es fundamental para la síntesis orgánica.
- Los métodos existentes a menudo requieren materiales de partida pre-funcionalizados.
- La expansión de la formación de enlaces C-C a materias primas fácilmente disponibles como los alquenos y los enlaces C-H es muy deseable.
Objetivo del estudio:
- Desarrollar una nueva transformación catalítica para la construcción de enlaces carbono-carbono.
- Para permitir el acoplamiento de alquenos con enlaces carbono-hidrógeno no activados.
- Ampliar el alcance de las adiciones de tipo Michael más allá de los compuestos carbonílicos α,β insaturados.
Principales métodos:
- Se utilizó un catalizador de paladio para la transformación.
- Empleó un grupo de dirección extraíble para controlar la selectividad regional.
- Se investigó el mecanismo de reacción mediante estudios estequiométricos.
Principales resultados:
- Se han formado con éxito enlaces carbono-carbono entre alquenos y varios nucleófilos C-H (1,3-dicarbonilos, carbonilos de arilo, aromáticos ricos en electrones).
- Se ha demostrado reactividad tipo Michael con alquenos no activados.
- Aplicaciones exhibidas en la diversificación de fármacos y la síntesis de productos naturales.
Conclusiones:
- La reacción catalizada por paladio desarrollada ofrece un método versátil para la formación de enlaces C-C.
- El uso de un grupo directivo garantiza una elevada selectividad regional.
- Esta transformación expande significativamente la utilidad de los alquenos y los enlaces C-H en la síntesis orgánica.
Videos de Conceptos Relacionados
02:17Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
18.1K
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...
18.1K
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
9.3K
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.
9.3K
02:36Regioselectivity and Stereochemistry of Hydroboration
9.6K
A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
9.6K
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
4.0K
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...
4.0K
02:13Reduction of Alkenes: Catalytic Hydrogenation
14.7K
Alkenes undergo reduction by the addition of molecular hydrogen to give alkanes. Because the process generally occurs in the presence of a transition-metal catalyst, the reaction is called catalytic hydrogenation.
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...
14.7K
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
21.7K
Introduction
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
21.7K