Video Experimental Relacionado
Updated: Feb 27, 2026
06:46
Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
8.0K
Ciclificación radical asimétrica de los azidoformatos de alilo a través de la catálisis metalorrádica basada en
Huiling Jiang1, Kai Lang2, Hongjian Lu1
1Department of Chemistry, University of South Florida , Tampa, Florida 33620, United States.
Journal of the American Chemical Society
|June 27, 2017
Resumen
Los catalizadores de cobalto (II) permiten una síntesis eficiente de aziridinas quirales cíclicas a partir de azidoformatos de alelo. Este enfoque metalúrgico logra altos rendimientos y selectividad para estructuras complejas de anillos fundidos.
Área de la Ciencia:
- Química organometálica
- Catálisis asimétrica
- Química orgánica sintética
Sus antecedentes:
- La catálisis metalloradical ofrece una poderosa estrategia para la formación de enlaces C-C y C-heteroátomo.
- Las aziridinas quirales son valiosos intermedios sintéticos para productos farmacéuticos y naturales.
- El desarrollo de métodos enantioselectivos para la construcción de sistemas cíclicos complejos sigue siendo un desafío importante.
Objetivo del estudio:
- Investigar la utilidad de la catálisis metaloradical a base de cobalto para las reacciones de biciclización radical.
- Desarrollar un método altamente enantioselectivo para la síntesis de estructuras bicíclicas fusionadas con aziridina/oxazolidinona.
- Identificar un catalizador quiral eficaz para la aziridinación intramolecular de los radicales de carbonilo.
Principales métodos:
- Se utilizó un complejo quiral D2-simétrico de cobalto (II) amidoporfirina (3,5-Di (tBu) - qingfirina) como catalizador metalúrgico.
- Se utilizan azidoformatos de alilo como sustratos para la aziridinación de radicales intramoleculares.
- Condiciones de reacción optimizadas para lograr altos rendimientos y estereoselectividad.
Principales resultados:
- Se ha demostrado con éxito la biciclización radical catalizada por el cobalto de los azidoformatos de alelo.
- Se obtiene una formación de alto rendimiento de aziridinas quirales [3.1.0]-bicíclicas sintéticamente útiles.
- Mostró una excelente diastereoselectividad y enantioselectividad en la formación de los productos bicíclicos.
Conclusiones:
- La catálisis metaloradical basada en cobalto es eficaz para la construcción de aziridinas quirales bicíclicas complejas.
- El catalizador quiral QingPhyrin permite una aziridinación radical intramolecular altamente estereoselectiva.
- Esta metodología proporciona una vía valiosa para el enriquecimiento enantiomérico de andamios cíclicos fundidos.
Videos de Conceptos Relacionados
01:27Radical Substitution: Allylic Bromination
6.7K
In organic synthesis, the formation of products can be altered by changing the reaction conditions. For example, a dibromo addition product is formed when propene is treated with bromine at room temperature. In contrast, propene undergoes allylic substitution in non-polar solvents at high temperatures to give 3-bromopropene. In order to avoid the addition reaction, the bromine concentration must be kept as low as possible throughout the reaction. This can be achieved using N-bromosuccinimide...
6.7K
01:21Radical Oxidation of Allylic and Benzylic Alcohols
3.0K
Activated manganese(IV) oxide can selectively oxidize allylic and benzylic alcohols via a radical intermediate mechanism. Primary allylic alcohols are oxidized to aldehydes, while secondary allylic alcohols yield ketones. The redox reaction of potassium permanganate with an Mn(II) salt such as manganese sulfate (under either alkaline or acidic conditions), followed by thorough drying, yields the oxidizing agent: activated MnO2. While MnO2 is insoluble in the solvents used for the reaction, the...
3.0K
01:25Radical Anti-Markovnikov Addition to Alkenes: Overview
4.3K
The addition of hydrogen bromide to alkenes in the presence of hydroperoxides or peroxides proceeds via an anti-Markovnikov pathway and yields alkyl bromides.
4.3K
01:31Radical Substitution: Allylic Chlorination
3.3K
Typically, when alkenes react with halogens at low temperatures, an addition reaction occurs. However, upon increasing the temperature or under reaction conditions that form radicals, providing a low but steady concentration of halogen radicals, allylic substitution reaction is favored. This is because allylic hydrogens are very reactive as the formed intermediate is resonance stabilized. For example, when propene is treated with chlorine in the gas phase at 400 °C, it undergoes allylic...
3.3K
01:27Cyclohexenones via Michael Addition and Aldol Condensation: The Robinson Annulation
3.0K
Robinson annulation is a base-catalyzed reaction for the synthesis of 2-cyclohexenone derivatives from 1,3-dicarbonyl donors (such as cyclic diketones, β-ketoesters, or β-diketones) and α,β-unsaturated carbonyl acceptors. Named after Sir Robert Robinson, who discovered it, this reaction yields a six-membered ring with three new C–C bonds (two σ bonds and one π bond).
3.0K
00:47Radical Formation: Addition
2.3K
Radicals can be formed by adding a radical to a spin-paired molecule. This is typically observed with unsaturated species, where the addition of a radical across the π bond leads to the production of a new radical by dissolving the π bond. For example, the addition of a Br radical to an alkene yields a carbon-centered radical.
Similar to charge conservation in chemical reactions, spin conservation is implicit for radical reactions. Accordingly, the product formed must possess an...
Similar to charge conservation in chemical reactions, spin conservation is implicit for radical reactions. Accordingly, the product formed must possess an...
2.3K