Video Experimental Relacionado

Updated: Jun 26, 2025

Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate

Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate

Published on: June 21, 2017

Mecanismo de la funcionalización alelica selectiva a través de sales de tiantreno

Karina Targos¹, Achyut R Gogoi², Ángel Rentería-Gómez²

¹Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States.

Journal of the American Chemical Society

|May 13, 2024

Resumen

Este estudio revela cómo las sales de tiantenio logran la funcionalización alelica Z-selectiva. Un paso clave de desprotonación dicta la reacción

Área de la Ciencia:

Química orgánica
Estudios sobre el mecanismo de reacción

Sus antecedentes:

La funcionalización alilica es crucial en la síntesis orgánica.
El logro de la estereoselectividad, particularmente la Z-selectividad, sigue siendo un desafío.

Objetivo del estudio:

Elucidar el mecanismo de la funcionalización alelica Z-selectiva utilizando sales de tiantenio.
Identificar los factores clave que rigen la estereoselectividad en esta reacción.

Principales métodos:

Análisis cinético detallado.
Experimentos de etiquetado con deuterio.
Métodos computacionales de la química.

Principales resultados:

La reacción procede a través de una desprotonación alilica que determina la velocidad y la estereodeterminación.
La configuración Z se establece en el intervalo de ylide.
Los pasos posteriores (protonación y sustitución nucleofílica) son rápidos e irreversibles.
Los estudios computacionales identificaron interacciones estabilizadoras en el estado de transición que favorecen la formación de Z-alqueno.

Conclusiones:

El mecanismo explica la selectividad Z observada en la aminación alelica.
La estabilización de las interacciones no vinculantes en el estado de transición es crítica para el estereocontrol.

Más Videos Relacionados

Efficient Synthesis of All-Carbon Quaternary Centers via the Conjugate Addition of Functionalized Monoorganozinc Bromides

Efficient Synthesis of All-Carbon Quaternary Centers via the Conjugate Addition of Functionalized Monoorganozinc Bromides

Published on: May 26, 2019

Preparation of N-2-alkoxyvinylsulfonamides from N-tosyl-1,2,3-triazoles and Subsequent Conversion to Substituted Phthalans and Phenethylamines

Preparation of N-2-alkoxyvinylsulfonamides from N-tosyl-1,2,3-triazoles and Subsequent Conversion to Substituted Phthalans and Phenethylamines

Published on: January 3, 2018

Videos de Conceptos Relacionados

Radical Substitution: Allylic Bromination

Radical Substitution: Allylic Bromination

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...

α-Bromination of Carboxylic Acids: Hell–Volhard–Zelinski Reaction

α-Bromination of Carboxylic Acids: Hell–Volhard–Zelinski Reaction

The method to achieve α-brominated carboxylic acids using a mixture of phosphorus tribromide and bromine is known as the Hell–Volhard–Zelinski reaction. The reaction is catalyzed by phosphorus tribromide, which can be used directly or produced in situ from red phosphorus and bromine. The mechanism comprises PBr3 catalyzed conversion of acid to acid bromide and hydrogen bromide. The acid bromide enolizes to its enol form in the presence of HBr. The nucleophilic enol attacks the...

Radical Substitution: Allylic Chlorination

Radical Substitution: Allylic Chlorination

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...

Electrophilic Addition to Alkynes: Halogenation

Electrophilic 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.

Electrophilic Addition to Alkynes: Hydrohalogenation

Electrophilic Addition to Alkynes: Hydrohalogenation

Electrophilic addition of hydrogen halides, HX (X = Cl, Br or I) to alkenes forms alkyl halides as per Markovnikov's rule, where the hydrogen gets added to the less substituted carbon of the double bond. Hydrohalogenation of alkynes takes place in a similar manner, with the first addition of HX forming a vinyl halide and the second giving a geminal dihalide.

Acid Halides to Alcohols: Grignard Reaction

Acid 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,...