Video Experimental Relacionado
Updated: May 15, 2026
09:35
Preparation of a Corannulene-functionalized Hexahelicene by Copper(I)-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
Published on: September 18, 2016
La alquenilación aromática C-H catalizada por Mn con las alquinas terminales
Bingwei Zhou1, Hui Chen, Congyang Wang
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
|January 5, 2013
Resumen
Este estudio introduce la primera alquenilación C-H catalizada por manganeso utilizando alquinas terminales. La reacción eficiente y selectiva produce E-olefinas anti-Markovnikov, lo que hace avanzar la síntesis orgánica catalítica.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La catálisis es la catálisis.
- Química organometálica Química orgánica de los metales.
Sus antecedentes:
- La funcionalización aromática C-H es crucial para la síntesis de moléculas orgánicas complejas.
- El desarrollo de sistemas catalíticos eficientes para la alquenilación C-H sigue siendo un desafío significativo.
- La catálisis de manganeso ofrece una alternativa rentable y sostenible a los catalizadores de metales preciosos.
Objetivo del estudio:
- Desarrollar el primer método catalizado por manganeso para la alquenilación aromática de C-H con alquinos terminales.
- Para lograr una alta quimio, regio y estereoselectividad en la reacción de alquenilación.
- Para dilucidar el mecanismo catalítico utilizando estudios experimentales y computacionales.
Principales métodos:
- Se utilizó un sistema de catalizador simple compuesto por carbonilo de bromuro de manganeso (MnBr(CO5) y dicilohexilamina (Cy2NH).
- Realizó reacciones de alquenilación aromática C-H con varias alquinas terminales.
- Se llevaron a cabo investigaciones experimentales y cálculos de la Teoría Funcional de Densidad (DFT) para comprender la vía de reacción.
Principales resultados:
- Se logró con éxito la primera alquenilación aromática C-H catalizada por manganeso con alquinas terminales.
- La reacción procedió con alta quimio, regio y estereoselectividad, produciendo olefinas de configuración E anti-Markovnikov en altos rendimientos.
- Intermedios clave identificados, incluidas las especies de manganciclo y alquinilamanganeso.
- Se determinó que la transferencia de hidrógeno de ligando a ligando y la activación de C-H asistida por alquinilo son pasos catalíticos cruciales.
Conclusiones:
- Estableció un protocolo de alquenilación C-H catalizado por manganeso operacionalmente simple y altamente eficiente.
- El método desarrollado proporciona una herramienta valiosa para construir E-olefinas con regioselectividad anti-Markovnikov.
- Los conocimientos mecanicistas contribuyen a una comprensión más amplia de las reacciones de activación y funcionalización de C-H catalizadas por el manganeso.
Videos de Conceptos Relacionados
02:27Preparation of Alkynes: Alkylation Reaction
Introduction
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
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.
02:34Preparation of Alkynes: Dehydrohalogenation
Introduction
Alkynes can be prepared by dehydrohalogenation of vicinal or geminal dihalides in the presence of a strong base like sodium amide in liquid ammonia. The reaction proceeds with the loss of two equivalents of hydrogen halide (HX) via two successive E2 elimination reactions.
Alkynes can be prepared by dehydrohalogenation of vicinal or geminal dihalides in the presence of a strong base like sodium amide in liquid ammonia. The reaction proceeds with the loss of two equivalents of hydrogen halide (HX) via two successive E2 elimination reactions.
02:38Electrophilic Addition to Alkynes: Halogenation
Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
01:11Nucleophilic Aromatic Substitution: Elimination–Addition
Simple aryl halides do not react with nucleophiles. However, nucleophilic aromatic substitutions can be forced under certain conditions, such as high temperatures or strong bases. The mechanism of substitution under such conditions involves the highly unstable and reactive benzyne intermediate. Benzyne contains equivalent carbon centers at both ends of the triple bond, each of which is equally susceptible to nucleophilic attack. This 50–50 distribution of products is confirmed through isotopic...