Video Experimental Relacionado
Updated: May 24, 2026
08:43
Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives
Published on: January 19, 2016
Hidroformilación altamente selectiva y asimétrica catalizada por Rh de las olefinas heterocíclicas
Samir H Chikkali1, Rosalba Bellini, Bas de Bruin
1Supramolecular and Homogeneous Catalysis, van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands.
Journal of the American Chemical Society
|March 20, 2012
Resumen
Los nuevos ligandos quirales del difosforo permiten una hidroformilación asimétrica altamente selectiva de las olefinas heterocíclicas más difíciles. Este avance logra excelentes rendimientos y enantioselectividades para aldehídos valiosos, avanzando la síntesis catalítica.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- Catalización asimétrica por catálisis asimétrica.
- Catálisis Homogénea.
Sus antecedentes:
- La hidroformilación asimétrica (AHF) es crucial para la síntesis de aldehídos quirales.
- El desarrollo de ligandos eficientes para el AHF de las olefinas heterocíclicas sigue siendo un desafío.
- Los métodos anteriores carecían de una alta regio- y enantioselectividad para sustratos heterocíclicos específicos.
Objetivo del estudio:
- Para sintetizar nuevos ligandos quirales del difosforo (fosfina-fosforamiditas y fosfina-fosfonitas).
- Para aplicar estos ligandos en la hidroformilación asimétrica catalizada por Rh de las olefinas heterocíclicas.
- Investigar la influencia de la estructura de los ligandos en el rendimiento catalítico, incluyendo la regio- y enantioselectividad.
Principales métodos:
- Síntesis de nuevos ligandos del difosforo: L1, L2 (fosfina-fosforamiditas) y L3a-c (fosfonitas de fosfina).
- Hidroformilación asimétrica catalizada por Rh de 2,3-dihidrofurano, 2,5-dihidrofurano, N-acetil-3-pirrolina y N-ter-butoxicarbonilo)-3-pirrolina. también conocido como N-acetil-3-pirrolina.
- Caracterización de los estados de reposo del catalizador utilizando espectroscopia de alta presión de RMN e IR.
Principales resultados:
- Los ligandos L1 y L2 lograron una coordinación selectiva y buenos rendimientos para la hidroformilación de 2,3-dihidrofurano.
- El ligando L3c demostró un cambio completo en la regioselectividad y alta enantioselectividad (hasta 91% ee) para el 2,5-dihidrofurano.
- Se lograron los EE más altos reportados para el AHF de dihidrofuranos y 3-pirrolinas, con una excelente regioselectividad para los derivados de pirrolina.
Conclusiones:
- Los nuevos ligandos difosforados son efectivos para el AHF catalizado por Rh de las olefinas heterocíclicas.
- El ligando L3c muestra una notable versatilidad, permitiendo el acceso a ambos enantiómeros de un aldehído objetivo mediante la modificación del sustrato.
- Este trabajo establece un nuevo punto de referencia para el AHF regio- y enantioselectivo de sustratos heterocíclicos desafiantes.
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.
02:47Alkynes 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.
02:24Reduction 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.
01:25Radical Anti-Markovnikov Addition to Alkenes: Overview
The addition of hydrogen bromide to alkenes in the presence of hydroperoxides or peroxides proceeds via an anti-Markovnikov pathway and yields alkyl bromides.