Video Experimental Relacionado

Updated: Mar 8, 2026

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

Dihalogenación vicinal altamente regioselectiva y enantioselectiva de las amidas de alilo

Bardia Soltanzadeh¹, Arvind Jaganathan², Yi Yi¹

¹Department of Chemistry, Michigan State University , East Lansing, Michigan 48824, United States.

Journal of the American Chemical Society

|January 24, 2017

Resumen

Este estudio introduce un nuevo método para la dihalogenación vicinal de las amidas de alilo, logrando una alta selectividad utilizando catalizadores y reactivos fácilmente disponibles. La reacción versátil funciona con varios alquenos y ofrece una base para una mayor química de halogenación.

Área de la Ciencia:

Química orgánica
Catálisis
Metodología sintética

Sus antecedentes:

La dihalogenación vicinal es una transformación crucial en la síntesis orgánica.
El desarrollo de métodos selectivos y eficientes para la dihalogenación sigue siendo un área activa de investigación.
Las amidas de alilo presentan desafíos y oportunidades únicas para la funcionalización.

Objetivo del estudio:

Desarrollar una dihalogenación vicinal altamente regio, diastereo y enantioselectiva de las amidas de alilo.
Explorar el alcance y las limitaciones de la metodología desarrollada.
Investigar la posibilidad de extender la reacción a la heterodihalogenación.

Principales métodos:

Se utilizó un enfoque controlado por catalizadores para la regioselectividad.
Se emplean catalizadores y fuentes de halenio disponibles en el mercado.
Se han incorporado sales de haluros inorgánicos de bajo costo como fuentes de haluros.

Principales resultados:

Se obtiene una alta regioselectividad, diastereoselectividad y enantioselectividad en la dihalogenación vicinal de las amidas de alilo.
Compatibilidad demostrada con los alquenos E y Z que contienen sustituyentes de arilo y alquilo.
Mostró la utilidad de sustratos electrónicamente imparciales debido al exquisito control del catalizador.
Presentó una investigación preliminar sobre la heterodihalogenación.

Conclusiones:

El método desarrollado ofrece una vía potente y selectiva para las amidas de alilo dihalogenadas vicinales.
La eficiencia de la reacción y el uso de reactivos accesibles la hacen atractiva para aplicaciones sintéticas.
Este trabajo sienta las bases para futuros desarrollos en estrategias de halogenación selectiva.

Más Videos Relacionados

Preparation of Contiguous Bisaziridines for Regioselective Ring-Opening Reactions

Preparation of Contiguous Bisaziridines for Regioselective Ring-Opening Reactions

Published on: July 28, 2022

Chemoselective Preparation of 1-Iodoalkynes, 1,2-Diiodoalkenes, and 1,1,2-Triiodoalkenes Based on the Oxidative Iodination of Terminal Alkynes

Chemoselective Preparation of 1-Iodoalkynes, 1,2-Diiodoalkenes, and 1,1,2-Triiodoalkenes Based on the Oxidative Iodination of Terminal Alkynes

Published on: September 12, 2018

Videos de Conceptos Relacionados

Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule

Regioselectivity 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...

Regioselectivity of Electrophilic Additions-Peroxide Effect

Regioselectivity of Electrophilic Additions-Peroxide Effect

In the presence of organic peroxides, the addition of hydrogen bromide to an alkene yields the isomer that is not predicted by Markovnikov’s rule. For example, the addition of hydrogen bromide to 2-methylpropene in the presence of peroxides gives 1-bromo-2-methylpropane. This addition reaction proceeds via a free radical mechanism, which reverses the regioselectivity. The free radical reaction mechanism involves three stages: initiation, propagation, and termination.

Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration

Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration

The rate of acid-catalyzed hydration of alkenes depends on the alkene's structure, as the presence of alkyl substituents at the double bond can significantly influence the rate.

Halogenation of Alkenes

Halogenation of Alkenes

Halogenation is the addition of chlorine or bromine across the double bond in an alkene to yield a vicinal dihalide. The reaction occurs in the presence of inert and non-nucleophilic solvents, such as methylene chloride, chloroform, or carbon tetrachloride.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.

Preparation of Alkynes: Dehydrohalogenation

Preparation of Alkynes: Dehydrohalogenation

Introduction
Alkynes can be prepared by dehydrohalogenation of vicinal or geminal dihalides in the presence of a strong base like sodium amide in liquid ammonia. The reaction proceeds with the loss of two equivalents of hydrogen halide (HX) via two successive E2 elimination reactions.

Acid-Catalyzed α-Halogenation of Aldehydes and Ketones

Acid-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...