Video Experimental Relacionado
Updated: Dec 15, 2025
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
3.9K
Hidrofuncionalización enantioselectiva controlada por catalizador y silano de alquenos por transferencia de átomos de
Kousuke Ebisawa1, Kana Izumi1, Yuka Ooka1
1Faculty of Pharmacy, Musashino University, 1-1-20 Shinmachi Nishitokyo-shi, Tokyo 202-8585, Japan.
Journal of the American Chemical Society
|July 11, 2020
Resumen
Este estudio introduce un nuevo método catalítico para sintetizar tetrahidrofuranos quirales utilizando un catalizador de cobalto. La reacción
Área de la Ciencia:
- Química orgánica
- Catálisis
- Metodología sintética
Sus antecedentes:
- Los tetrahidrofuranos son motivos estructurales cruciales en numerosos productos naturales biológicamente activos.
- La síntesis enantioselectiva eficiente de estos compuestos sigue siendo un desafío importante en la química orgánica.
Objetivo del estudio:
- Desarrollar una nueva síntesis catalítica enantioselectiva de tetrahidrofuranos.
- Para aclarar el mecanismo de la reacción, que involucra la transferencia de átomos de hidrógeno catalizados por metales de transición (TM-HAT) y el cruce radical-polar (RPC).
Principales métodos:
- Utilización de un catalizador quiral de cobalto para la hidroalcoxilación de alquenos no conjugados.
- Utilizando el tetrafluoroborato de *N*-fluoro-2,4,6-colidinio y el dietilsilano como reactivos clave.
- Investigar los parámetros de reacción, incluidos el obstáculo estérico del silano, la velocidad de adición, los efectos del disolvente y la temperatura.
Principales resultados:
- Se ha logrado una síntesis eficiente de tetrahidrofuranos con una enantioselectividad excelente (hasta el 94% ee).
- Se descubrió que la configuración absoluta del producto depende en gran medida del obstáculo estérico del silano.
- Se identificaron dos mecanismos selectivos competidores que influyen en el resultado estereoquímico, respaldados por datos experimentales y computacionales.
Conclusiones:
- El método desarrollado proporciona una vía versátil para los tetrahidrofuranos enriquecidos enantioméricamente.
- El estudio revela un escenario mecanicista sin precedentes que involucra vías competidoras dictadas por la estructura silana.
- Este trabajo ofrece nuevos conocimientos sobre el control de la estereoquímica en las reacciones radicales catalizadas por metales de transición.
Videos de Conceptos Relacionados
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
3.8K
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...
3.8K
02:13Reduction of Alkenes: Catalytic Hydrogenation
13.8K
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...
13.8K
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
8.8K
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.
8.8K
01:25Radical Anti-Markovnikov Addition to Alkenes: Overview
3.9K
The addition of hydrogen bromide to alkenes in the presence of hydroperoxides or peroxides proceeds via an anti-Markovnikov pathway and yields alkyl bromides.
3.9K
02:44Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
12.3K
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.
12.3K
02:36Regioselectivity and Stereochemistry of Hydroboration
9.2K
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.
9.2K