Video Experimental Relacionado
Updated: Jul 5, 2026
09:08
Separation of Aldehydes and Reactive Ketones from Mixtures Using a Bisulfite Extraction Protocol
Published on: April 2, 2018
El primer método general para la olefinación Z-selectiva de acilsilanos a través de aniones enolatos que proporcionan
Mitsuru Shindo1, Kenji Matsumoto, Seiji Mori
1Institute for Medicinal Resources, University of Tokushima, Sho-machi 1, Tokushima 770-8505, Japan. shindo@ph2.tokushima-u.ac.jp
Journal of the American Chemical Society
|June 13, 2002
Resumen
Los investigadores crearon un nuevo método de olefinación estereoselectiva para los acilsilanos. Este proceso produce ésteres (Z) -beta-silyl-alfa, beta-insaturados, valiosos para la síntesis de alquenos complejos.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- Química sintética de la química sintética.
Sus antecedentes:
- La síntesis estereoselectiva es crucial para crear moléculas orgánicas complejas.
- Las reacciones de olefinación son transformaciones fundamentales en la química orgánica.
Objetivo del estudio:
- Desarrollar un método general y estereoselectivo para la olefinación de acilsilanos.
- Para sintetizar los ésteres (Z) -beta-silyl-alfa y beta-insaturados.
Principales métodos:
- Utilizando aniones de ynolato generados a partir de acilsilanos.
- Empleando una nueva reacción de olefinación estereoselectiva.
Principales resultados:
- Desarrollo exitoso del primer método general para la olefinación estereoselectiva de acilsilanos.
- Producción de ésteres (Z) -beta-silyl-alfa y beta-insaturados.
- Utilidad demostrada en el acceso a los alquenos tri y tetrasubstituidos.
Conclusiones:
- El método desarrollado proporciona una ruta fácil a valiosos ésteres insaturados de beta-sililo.
- Esta metodología amplía el conjunto de herramientas sintéticas para la construcción de alquenos altamente sustituidos con una estereoquímica definida.
Videos de Conceptos Relacionados
02:11Leveling Effect and Non-Aqueous Acid-Base Solutions
This lesson defines the leveling effect in acidic and basic solutions and its role in aqueous and non-aqueous solutions. It is essential to understand the competing nature of various species in a chemical system.
The Leveling Effect of a Solvent
A generic acid (HA) reacts with the generic base (B-) to yield the corresponding conjugate base (A-) and conjugate acid (HB):
The Leveling Effect of a Solvent
A generic acid (HA) reacts with the generic base (B-) to yield the corresponding conjugate base (A-) and conjugate acid (HB):
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...
02:25Elimination Reactions
A nucleophile can react with an alkyl halide to give the substitution product by displacing the halogen. Or it can function as a base to give the elimination product by deprotonation of the neighboring carbon to form an alkene. In an elimination reaction, the substrate loses two groups from adjacent carbons forming at least one π bond. The carbon attached to the halogen is called the α carbon, while the adjacent carbon is called the β carbon; hence, these reactions are called β elimination or...
01:15Nucleophilic Acyl Substitution of Carboxylic Acid Derivatives
Nucleophilic acyl substitution is an important class of substitution reactions involving a nucleophile and an acyl compound, such as carboxylic acids and their derivatives. In these reactions, the leaving group attached to the acyl group is substituted by a nucleophile. The general mechanism proceeds via two steps.
01:21Acid-Catalyzed α-Halogenation of Aldehydes and Ketones
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...
01:10Factors Affecting α-Alkylation of Ketones: Choice of Base
α-Alkylation of ketones is achieved in the presence of alkyl halides and a base. The reaction proceeds via the formation of an enolate ion followed by nucleophilic substitution. The choice of base employed is essential as it is the key factor in determining the reaction outcome.
The reaction involving bases like EtO− whose conjugate acid EtOH (pKa = 15.9) is stronger than the ketone (pKa = 19.2) results in an equilibrium mixture with higher ketone concentration. As a consequence, side reactions...
The reaction involving bases like EtO− whose conjugate acid EtOH (pKa = 15.9) is stronger than the ketone (pKa = 19.2) results in an equilibrium mixture with higher ketone concentration. As a consequence, side reactions...