Video Experimental Relacionado
Updated: May 11, 2026
09:45
A Protocol for Safe Lithiation Reactions Using Organolithium Reagents
Published on: November 12, 2016
Preparación y reacciones de reactivos de Grignard enantioméricamente puros y α-funcionalizados
Peter J Rayner1, Peter O'Brien, Richard A J Horan
1Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom.
Journal of the American Chemical Society
|May 8, 2013
Resumen
Este estudio presenta un nuevo método para crear reactivos de Grignard quirales enantioméricamente puros. Este enfoque evita ligandos quirales específicos y ofrece una ruta versátil a valiosos intermediarios sintéticos.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- Síntesis asimétrica de síntesis.
- Química organometálica Química orgánica de los metales.
Sus antecedentes:
- Los reactivos de Chiral Grignard son componentes esenciales en la síntesis orgánica.
- Los métodos existentes para su preparación a menudo requieren ligandos quirales específicos o condiciones duras.
- El desarrollo de estrategias eficientes y versátiles para los reactivos de Grignard enantioméricamente puros sigue siendo un desafío clave.
Objetivo del estudio:
- Desarrollar una nueva estrategia para la síntesis de reactivos de Grignard enantioméricamente puros α-alcoxi y α-amino.
- Explorar una alternativa a los ligandos quirales tradicionales en los protocolos de desprotonación asimétrica.
- Establecer un método robusto para generar valiosos intermedios quirales.
Principales métodos:
- Deprotonación asimétrica de sulfóxidos utilizando sec-butilitio y una diamina quiral.
- Atrapar las especies litidas resultantes con el sulfinato de Andersen (derivado del mentol).
- El intercambio posterior de magnesio y halógeno y el atrapamiento electrófilo para obtener productos funcionalizados.
Principales resultados:
- Se han logrado altas relaciones diastereoméricas (dr ≥99:1) y relaciones enantioméricas (er ≥99:1) para los sulfóxidos α-alcoxi y α-amino.
- Se ha demostrado la generación eficiente de reactivos Grignard enantioméricamente puros α-funcionalizados a través del intercambio sulfóxido-magnesio.
- Demostró la capacidad de acceder a cualquiera de los enantiómeros de los productos finales sin usar (-) -sparteína.
- Se observó una falta de estereospecificidad en el azufre durante la etapa inicial de desprotonación/atrapamiento.
- Se confirmó la estabilidad de configuración del reactivo de Grignard sustituido por α-alcoxi a temperatura ambiente durante 30 minutos.
Conclusiones:
- La estrategia desarrollada proporciona una ruta fácil y eficiente a los reactivos α-alcoxi y α-amino de Grignard enantioméricamente puros.
- Este método ofrece una alternativa valiosa para la síntesis asimétrica, evitando la necesidad de ligandos quirales específicos como la (-) -sparteína.
- Los hallazgos contribuyen al avance de las metodologías sintéticas para la construcción de moléculas quirales complejas.
Más Videos Relacionados
08:12A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species
Published on: August 16, 2018
06:31Highly Stereoselective Synthesis of 1,6-Ketoesters Mediated by Ionic Liquids: A Three-component Reaction Enabling Rapid Access to a New Class of Low Molecular Weight Gelators
Published on: November 27, 2015
Videos de Conceptos Relacionados
01:15Acid Halides to Alcohols: Grignard Reaction
Organomagnesium halides, commonly known as Grignard reagents, convert acid halides to tertiary alcohols. The reaction requires two equivalents of the Grignard reagent and proceeds via a ketone intermediate.
Grignard reagents are a source of carbanions and function as nucleophiles. The mechanism begins with the nucleophilic attack by the carbanion at the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs,...
Grignard reagents are a source of carbanions and function as nucleophiles. The mechanism begins with the nucleophilic attack by the carbanion at the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs,...
01:13Preparation of Carboxylic Acids: Carboxylation of Grignard Reagents
Carboxylic acids can be prepared by the carboxylation of Grignard reagents (RMgX). This method is convenient for converting alkyl (primary, secondary or tertiary), vinyl, benzyl, and aryl halides to carboxylic acids with one additional carbon than the starting RMgX.
02:00Alcohols from Carbonyl Compounds: Grignard Reaction
Grignard reagents are one of the most commonly used reagents used to synthesize alcohols from carbonyl compounds. Grignard reagents are organomagnesium halides with a highly polar carbon–magnesium bond. Due to the partial ionic nature of the C–Mg bond, the carbon functions as a strong nucleophile and attacks electrophiles like carbonyl carbon.
Magnesium from the reagent coordinates with carbonyl oxygen, further reducing the carbonyl carbon's electron density. Thus, the carbonyl carbon is a...
Magnesium from the reagent coordinates with carbonyl oxygen, further reducing the carbonyl carbon's electron density. Thus, the carbonyl carbon is a...
01:08Esters to Alcohols: Grignard Reaction
The reaction of an ester with a Grignard reagent, followed by hydrolysis of the magnesium alkoxide salt in aqueous acid, yields a tertiary alcohol. In the case of formate esters, secondary alcohols are formed.
The reaction requires two equivalents of the Grignard reagent and introduces two identical alkyl groups, derived from the Grignard reagent, bonded to the hydroxyl-bearing carbon of the alcohol.
The reaction follows the typical nucleophilic acyl substitution mechanism. The Grignard...
The reaction requires two equivalents of the Grignard reagent and introduces two identical alkyl groups, derived from the Grignard reagent, bonded to the hydroxyl-bearing carbon of the alcohol.
The reaction follows the typical nucleophilic acyl substitution mechanism. The Grignard...
00:57Nitriles to Ketones: Grignard Reaction
Organomagnesium halides, commonly known as Grignard reagents, convert nitriles to ketones and proceed through a nucleophilic acyl substitution. Nitriles react with a Grignard reagent, followed by an aqueous acid, to yield ketones. The reaction introduces a new carbon–carbon bond. The alkyl–magnesium bond in the Grignard reagent is highly polar, so the alkyl carbon develops a carbanionic character and acts as a nucleophile.
The mechanism begins with a nucleophilic attack by the Grignard reagent...
The mechanism begins with a nucleophilic attack by the Grignard reagent...
01:26Synthesis of α-Substituted Carbonyl Compounds: The Stork Enamine Reaction
α-Substituted ketones or aldehydes can be synthesized from enamines by the Stork enamine reaction, named after its pioneer Gilbert Stork. Enamines are useful synthetic intermediates where the lone pair on nitrogen is in conjugation with the C=C bond. They resemble enolate ions, as the resonance forms of both species have a nucleophilic α carbon.