Video Experimental Relacionado
Updated: Oct 14, 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
3.7K
Funcionalización α-C-H selectiva del sitio de las trialquilaminas mediante catálisis reversible de transferencia de
Yangyang Shen1, Ignacio Funez-Ardoiz2, Franziska Schoenebeck2
1Department of Chemistry, Columbia University, New York, New York 10027, United States.
Journal of the American Chemical Society
|November 5, 2021
Resumen
Este estudio introduce un nuevo método para funcionalizar selectivamente las trialquilaminas en posiciones estéricamente obstaculizadas, superando las limitaciones anteriores en la activación del enlace C-H para el descubrimiento de fármacos.
Área de la Ciencia:
- Química orgánica
- Catálisis
- Química medicinal
Sus antecedentes:
- Las trialquilaminas son bloques de construcción cruciales en los productos farmacéuticos y naturales.
- La funcionalización selectiva de las trialquilaminas es un desafío debido al obstáculo estérico.
- Los métodos actuales favorecen los sitios menos concurridos, limitando la utilidad sintética.
Objetivo del estudio:
- Desarrollar un método para la funcionalización selectiva del enlace α-C ((sp3) -H de las triquilaminas en posiciones estéricamente obstaculizadas.
- Para superar el control estérico en la funcionalización de la triquilamina.
- Permitir la síntesis simplificada y la modificación en etapas avanzadas de los agentes farmacéuticos.
Principales métodos:
- Utilizando la transferencia reversible de átomos de hidrógeno para establecer un equilibrio entre los enlaces α-amino C ((sp3) -H y un radical tiol.
- Empleando un paso de captura de radicales más lento con olefinas deficientes en electrones.
- Aplicando el principio de Curtin-Hammett para guiar la selectividad hacia el radical α-amino más abarrotado.
Principales resultados:
- Se logra la formación selectiva de enlaces C ((sp3) -C ((sp3)) en el sitio α-amino más poblado.
- Se ha demostrado una alta selectividad del sitio y utilidad preparatoria en diversas trialquilaminas.
- Se estableció una guía predictiva cualitativa para la selectividad del sitio utilizando desplazamientos de RMN 13C.
Conclusiones:
- Este sistema dinámico ofrece un nuevo enfoque estratégico para la funcionalización directa de C-H.
- El método facilita la formación de centros de carbono cuaternarios sustituidos por N.
- El enfoque tiene un potencial significativo para acelerar el descubrimiento de fármacos de moléculas pequeñas y agilizar la síntesis.
Videos de Conceptos Relacionados
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
3.5K
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...
3.5K
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
8.3K
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.
8.3K
02:17Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
14.9K
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...
14.9K
01:30Preparation of Amines: Alkylation of Ammonia and Amines
3.8K
Alkylation is one of the methods used to prepare amines. Direct alkylation of ammonia or a primary amine with an alkyl halide gives polyalkylated amines along with a quaternary ammonium salt through successive SN2 reactions. This process of making the quaternary salt through the direct alkylation method is called exhaustive alkylation.
Each alkylation step makes the nitrogen center more nucleophilic, which triggers successive alkylations until a quaternary ammonium salt is formed. Considering...
Each alkylation step makes the nitrogen center more nucleophilic, which triggers successive alkylations until a quaternary ammonium salt is formed. Considering...
3.8K
01:19Diazonium Group Substitution: –OH and –H
3.0K
Nitrous acid, a weak acid, is prepared in situ via the reaction of sodium nitrite with a strong acid under cold conditions. This nitrous acid prepared in situ reacts with primary arylamines to form arenediazonium salts. Such reactions are known as diazotization reactions. As shown in Figure 1, the formation of arenediazonium salts begins with the decomposition of nitrous acid in an acidic solution to give nitrosonium ions.
3.0K
01:21Acid-Catalyzed α-Halogenation of Aldehydes and Ketones
4.1K
By replacing an α-hydrogen with a halogen, acid-catalyzed α-halogenation of aldehydes or ketones yields a monohalogenated product
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
4.1K