Video Experimental Relacionado
Updated: May 8, 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
Hidrogenación altamente estereoselectiva catalizada por borano libre de metales de las piridinas
1Beijing National Laboratory of Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
Journal of the American Chemical Society
|August 16, 2013
Resumen
Este estudio introduce un método libre de metales para la hidrogenación de piridina utilizando catalizadores de borano generados in situ. El proceso produce eficientemente varias piperidinas con altos rendimientos y excelente estereoselectividad cis.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La catálisis de la catálisis.
- Química verde es la química verde.
Sus antecedentes:
- La hidrogenación de la piridina es crucial para sintetizar las piperidinas, importantes bloques de construcción farmacéuticos.
- Los métodos existentes a menudo se basan en catalizadores de metales preciosos, lo que plantea preocupaciones ambientales y de costos.
- El desarrollo de sistemas catalíticos libres de metales sigue siendo un desafío importante en la síntesis orgánica.
Objetivo del estudio:
- Desarrollar un nuevo sistema catalítico sin metales para la hidrogenación directa de las piridinas.
- Para lograr altos rendimientos y una excelente estereoselectividad en la reducción de piridinas a piperidinas.
- Para utilizar materiales de partida fácilmente disponibles y un enfoque catalítico sencillo.
Principales métodos:
- Generación in situ de catalizadores de borano homogéneos a partir de alquenos y bis (pentafluorofenil) borano (HB (C6F5) 2).
- Hidrogenación directa de varios sustratos de piridina utilizando los catalizadores de boro generados.
- Análisis de los productos de reacción utilizando técnicas estándar de química orgánica (por ejemplo, RMN, GC-MS) para determinar el rendimiento y la estereoselectividad.
Principales resultados:
- Se logró una hidrogenación directa sin metales exitosa de una amplia gama de piridinas.
- Se obtuvieron altos rendimientos de las piperidinas correspondientes en varios sustratos.
- Se observaron excelentes estereoselectividades cis en los productos de hidrogenación.
Conclusiones:
- El método desarrollado ofrece una alternativa eficiente y sostenible para la hidrogenación de piridina.
- Los catalizadores de borano generados in situ proporcionan una plataforma versátil para sintetizar valiosos derivados de piperidina.
- Este enfoque libre de metales contribuye a estrategias sintéticas más ecológicas en la química orgánica.
![[(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)
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...
02:36Regioselectivity and Stereochemistry of Hydroboration
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.
03:08Hydroboration-Oxidation of Alkenes
In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.
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.
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
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.
02:13Reduction of Alkenes: Catalytic Hydrogenation
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 surface of...
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 surface of...