Video Experimental Relacionado
Updated: Jun 10, 2026
06:46
Facile Preparation of (2Z,4E)-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
Adición conjugada asimétrica catalítica directa de alcinos terminales a los tioamidos alfa, beta insaturados
Ryo Yazaki1, Naoya Kumagai, Masakatsu Shibasaki
1Institute of Microbial Chemistry, Tokyo, 3-14-23 Kamiosaki, Shinagawa-ku, Tokyo 141-0021, Japan.
Journal of the American Chemical Society
|July 29, 2010
Resumen
Este estudio introduce un nuevo método catalítico para crear alquinilación enantioselectiva de tioamidas. Este enfoque utiliza la catálisis cooperativa para la síntesis eficiente de las valiosas beta-alquiniltioamidas.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- Catalización asimétrica por catálisis asimétrica.
- Metodología sintética de la metodología sintética.
Sus antecedentes:
- Las reacciones de adición conjugada son fundamentales en la síntesis orgánica.
- El desarrollo de métodos enantioselectivos para la funcionalización de compuestos insaturados sigue siendo un desafío clave.
- Las tioamidas ofrecen una reactividad única, pero son menos exploradas en adiciones conjugadas asimétricas.
Objetivo del estudio:
- Desarrollar una adición conjugada asimétrica catalítica directa de alquinas terminales a tioamidas alfa, beta insaturadas.
- Para lograr una alta enantioselectividad en la formación de beta-alquiniltioamidas.
- Explorar la utilidad sintética de los productos resultantes.
Principales métodos:
- Se utilizó la catálisis cooperativa ácido de Lewis blando/base de Brønsted dura.
- Se emplearon condiciones de transferencia de protones para la reacción.
- Investigó los mecanismos de reacción a través de experimentos de control.
Principales resultados:
- Se obtiene adición conjugada asimétrica catalítica directa de alquinas terminales a tioamidas alfa, beta insaturadas.
- Se ha demostrado una alta enantioselectividad en la síntesis de beta-alquiniltioamidas.
- Identificó el enolato de tioamida de cobre como un intermediario clave que actúa como una base de Brønsted.
Conclusiones:
- La catálisis cooperativa permite la activación simultánea de alquinas y tioamidas.
- La transferencia de protones es crucial para impulsar el ciclo catalítico.
- Los productos de alquinilación exhiben un potencial de transformación divergente, mostrando su utilidad sintética.
Videos de Conceptos Relacionados
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.
01:09Conjugate Addition to α,β-Unsaturated Carbonyl Compounds
α,β-Unsaturated carbonyl compounds are molecules bearing a carbonyl and alkene functionality in conjugation with each other. The conjugation in the molecule leads to three resonance structures. The hybrid form exhibits two probable electrophilic sites: the carbonyl carbon and the β carbon.
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.
01:27Conjugate Addition (1,4-Addition) vs Direct Addition (1,2-Addition)
α,β-Unsaturated carbonyl compounds with two electrophilic sites, the carbonyl carbon, and the β carbon, are susceptible to nucleophilic attack via two modes: conjugate or 1,4-addition and direct or 1,2-addition.
Conjugate addition results in a thermodynamically stable product. The reaction retains the stronger C=O bond at the expense of the weaker C=C π bond. The process is slow as the β carbon is less electrophilic than the carbonyl carbon.
Direct addition products are formed faster owing to...
Conjugate addition results in a thermodynamically stable product. The reaction retains the stronger C=O bond at the expense of the weaker C=C π bond. The process is slow as the β carbon is less electrophilic than the carbonyl carbon.
Direct addition products are formed faster owing to...
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.