Video Experimental Relacionado
Updated: Mar 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
4.1K
Hidrogenación altamente enantioselectiva de amidas mediante resolución cinética dinámica a baja presión y temperatura
Loorthuraja Rasu1, Jeremy M John1, Elanna Stephenson1
1Department of Chemistry, University of Alberta , Edmonton, Alberta T6G 2G2, Canada.
Journal of the American Chemical Society
|January 31, 2017
Resumen
Un nuevo sistema catalítico produce eficientemente alcoholes quirales a partir de amidas utilizando resolución cinética dinámica. Este método logra altos rendimientos y una excelente enantioselectividad en condiciones suaves, avanzando la síntesis asimétrica.
Área de la Ciencia:
- Química orgánica
- Catálisis asimétrica
- Química ecológica
Sus antecedentes:
- El desarrollo de sistemas catalíticos eficientes para la síntesis asimétrica es crucial para la producción de compuestos enantioméricos puros.
- La resolución cinética dinámica (DKR) ofrece una poderosa estrategia para convertir los materiales de partida racémicos en enantiómeros individuales.
Objetivo del estudio:
- Desarrollar y optimizar un nuevo sistema catalítico para la hidrogenación asimétrica de amidas funcionalizadas.
- Para lograr un alto rendimiento y enantioselectividad en la síntesis de alcoholes quirales a través de DKR.
Principales métodos:
- Cribado combinado de alto rendimiento y optimización a escala de laboratorio para identificar las condiciones catalíticas óptimas.
- Se utilizó un catalizador específico de rutenio trans-RuCl2 (((S,S) -skewphos) (((R,R) -dpen) con isopropoxido de sodio (2-PrONa) en isopropanol (2-PrOH).
- Se realizó la hidrogenación de α-fenoxi y amidas relacionadas en condiciones suaves (temperatura ambiente, 4 atm H2).
Principales resultados:
- Desarrolló un sistema catalítico eficiente que incluye trans-RuCl2 (((S,S) -skewphos) (((R,R) -dpen), 2-PrONa y 2-PrOH.
- Se obtienen altos rendimientos (hasta el 99%) y un excelente exceso enantiomérico (superior al 99% ee) para los alcoholes quirales.
- Demostró la eficacia del sistema a temperatura ambiente y baja presión de hidrógeno (4 atm).
Conclusiones:
- El sistema catalítico desarrollado es muy eficaz para la hidrogenación asimétrica de amidas mediante DKR.
- El método proporciona una vía práctica y eficiente para obtener alcoholes quirales valiosos con un excepcional control estereoquímico.
- Este trabajo contribuye al avance de metodologías de síntesis asimétricas sostenibles y eficientes.
Videos de Conceptos Relacionados
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
14.6K
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...
14.6K
01:29Preparation of Amides
4.2K
Amides are synthesized by treating carboxylic acids with amines in the presence of dehydrating agents like dicyclohexylcarbodiimide (DCC).
The DCC-promoted synthesis of amides begins with the protonation of DCC by carboxylic acid. The protonation makes it a better acceptor. Next, the addition of carboxylate to the protonated carbodiimide gives a reactive acylating agent.
Subsequently, the amine acts as a nucleophile that attacks the acylating agent to form a tetrahedral intermediate. In the...
The DCC-promoted synthesis of amides begins with the protonation of DCC by carboxylic acid. The protonation makes it a better acceptor. Next, the addition of carboxylate to the protonated carbodiimide gives a reactive acylating agent.
Subsequently, the amine acts as a nucleophile that attacks the acylating agent to form a tetrahedral intermediate. In the...
4.2K
01:13Preparation of Amines: Reduction of Amides and Nitriles
3.2K
Nitriles can be reduced to primary amines using reducing agents like lithium aluminum hydride or catalytic hydrogenation. The reduction introduces an amino group with an extra carbon in the skeleton. Nitriles are formed from the reaction between alkyl halides and sodium cyanide through the SN2 mechanism. Primary alkyl halides are the preferred substrates to prepare nitriles.
Amides can be reduced to primary, secondary, and tertiary amines using catalytic hydrogenation, active metals like Fe,...
Amides can be reduced to primary, secondary, and tertiary amines using catalytic hydrogenation, active metals like Fe,...
3.2K
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
9.2K
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.
9.2K
01:22Preparation of 1° Amines: Azide Synthesis
4.7K
Direct alkylation of ammonia produces polyalkylated amines, along with a quaternary ammonium salt. To exclusively prepare primary amines, the azide synthesis method can be used.
Azide ions act as good nucleophiles and react with unhindered alkyl halides to form alkyl azides. Alkyl azides do not participate in further nucleophilic substitution reactions, thereby eliminating the chances of polyalkylated products. Alkyl azides are reduced by hydride-based reducing agents, like lithium aluminum...
Azide ions act as good nucleophiles and react with unhindered alkyl halides to form alkyl azides. Alkyl azides do not participate in further nucleophilic substitution reactions, thereby eliminating the chances of polyalkylated products. Alkyl azides are reduced by hydride-based reducing agents, like lithium aluminum...
4.7K