Video Experimental Relacionado
Updated: Jul 20, 2026
11:51
Facile Preparation of 4-Substituted Quinazoline Derivatives
Published on: February 15, 2016
Los sustitutos de las metidas de quinona modulan fuertemente la formación y la estabilidad de sus adyuctos
Emily E Weinert1, Ruggero Dondi, Stefano Colloredo-Melz
1Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA.
Journal of the American Chemical Society
|September 7, 2006
Resumen
Los efectos electrónicos sobre las metidas de quinona (QM) controlan su reactividad con los desoxinucleósidos. Los grupos donantes de electrones estabilizan la QM, mientras que los grupos que retiran electrones la desestabilizan, lo que permite un control predecible sobre las reacciones de la QM.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La cinética química es la cinética química.
- La bioquímica es la bioquímica.
Sus antecedentes:
- Las metidas de quinona (QM) son intermediarios reactivos cruciales en varias reacciones químicas.
- Comprender los factores que influyen en la estabilidad y la reactividad de QM es esencial para controlar los resultados de la reacción.
- La interacción de QM con los desoxinucleósidos es relevante para el daño del ADN y los mecanismos de reparación.
Objetivo del estudio:
- Investigar cómo las perturbaciones electrónicas afectan la estabilidad y la reactividad de los metidos de quinona.
- Para dilucidar la cinética y los perfiles de producto de las reacciones de QM con desoxinucleósidos.
- Para demostrar el ajuste predecible de la reversibilidad de la reacción QM a través de efectos de sustitución.
Principales métodos:
- Síntesis de precursores de metido de quinona (QMP) con diversos sustituyentes electrónicos.
- Estudios de estabilidad de los adductos de metido de quinona y desoxinucleósido.
- Fotólisis de flash láser para medir las tasas de adición nucleofílica a los QM sustituidos.
Principales resultados:
- Los sustituyentes donantes de electrones estabilizan la QM, aumentando la estabilidad del adducto y disminuyendo las velocidades de reacción.
- Los sustituyentes que retiran electrones desestabilizan la QM, disminuyendo la estabilidad del adducto y aumentando las tasas de reacción.
- Las velocidades de reacción abarcan cinco órdenes de magnitud, en correlación con las propiedades electrónicas de los sustituyentes.
Conclusiones:
- La naturaleza electrónica de los sustituyentes de las metidas de quinona modula de manera predecible su estabilidad y reactividad.
- Este control permite ajustar la cinética y la reversibilidad de las reacciones QM con desoxinucleósidos.
- Los hallazgos tienen implicaciones para el diseño de procesos químicos y la comprensión de las interacciones biológicas que involucran QM.
![Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F60786.jpg&w=3840&q=50)
Videos de Conceptos Relacionados
01:17Oxidation of Phenols to Quinones
In the presence of oxidizing agents, phenols are oxidized to quinones. Quinones can be easily reduced back to phenols using mild reducing agents. The electron-donating hydroxyl group enhances the reactivity of the aromatic ring, enabling oxidation of the ring even in the absence of an α hydrogen.
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox property is crucial in...
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox property is crucial in...
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...
01:13meta-Directing Deactivators: –NO2, –CN, –CHO, –CO2R, –COR, –CO2H
All meta-directing substituents are deactivating groups. These substituents withdraw electrons from the aromatic ring, making the ring less reactive toward electrophilic substitution. For example, the nitration of nitrobenzene is 100,000 times slower than that of benzene because of the deactivating effect of the nitro group. The first step in an electrophilic aromatic substitution is the addition of an electrophile to form a resonance-stabilized carbocation. The energy diagrams for the...
01:09Directing Effect of Substituents: meta-Directing Groups
Substituents on the benzene ring that direct an incoming electrophile to undergo substitution at the meta position are called meta directors. All meta directors either have a positive charge on the atom directly bonded to the ring or a partial positive charge. These groups function by withdrawing electrons from the ring through inductive and resonance effects. Consider the carbocation intermediates formed upon the addition of an electrophile on nitrobenzene at the ortho, meta, and para...
02:34Nucleophilic Substitution Reactions
Historical perspective
In 1896, the German chemist Paul Walden discovered that he could interconvert pure enantiomeric (+) and (-) malic acids through a series of reactions. This conversion suggested the involvement of optical inversion during the substitution reaction. Further, in 1930, Sir Christopher Ingold described for the first time two different forms of nucleophilic substitution reactions, which are known as SN1 (nucleophilic substitution unimolecular) and SN2 (nucleophilic substitution...
In 1896, the German chemist Paul Walden discovered that he could interconvert pure enantiomeric (+) and (-) malic acids through a series of reactions. This conversion suggested the involvement of optical inversion during the substitution reaction. Further, in 1930, Sir Christopher Ingold described for the first time two different forms of nucleophilic substitution reactions, which are known as SN1 (nucleophilic substitution unimolecular) and SN2 (nucleophilic substitution...
02:17Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
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...