Video Experimental Relacionado

Updated: Dec 29, 2025

A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species

A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species

Published on: August 16, 2018

Acoplamiento doblemente enantioconvergente controlado por catalizador de nucleófilos y electrófilos alquilo racémicos

Haohua Huo¹, Bradley J Gorsline¹, Gregory C Fu²

¹Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.

Science (New York, N.Y.)

|February 1, 2020

Resumen

Este estudio introduce un nuevo catalizador quiral de níquel para la creación de enlaces carbono-carbono. Este catalizador logra un acoplamiento doblemente estereoconvergente de los materiales de partida racémicos, dando como resultado un único estereoisómero del producto.

Área de la Ciencia:

Química orgánica
Catálisis
Metodología sintética

Sus antecedentes:

El control estereoquímico en la formación de enlaces carbono-carbono es un desafío significativo en la síntesis orgánica.
Los métodos tradicionales como las reacciones S_N1 y S_N2 tienen limitaciones en el alcance y el estereocontrol, especialmente con materiales de partida racémicos.

Objetivo del estudio:

Desarrollar un método catalítico para la formación estereoselectiva de enlaces carbono-carbono.
Abordar las limitaciones de las reacciones de sustitución clásicas en el control de la estereoquímica de los precursores racémicos.

Principales métodos:

Desarrollo de un catalizador quiral de níquel.
Acoplamiento de haluros propárgicos racémicos (electrófilos) con amidas β-zincadas racémicas (nucleófilos).

Principales resultados:

Se logró un acoplamiento doblemente estereoconvergente, formando un nuevo enlace carbono-carbono.
Generado un solo estereoisómero del producto a partir de dos reactivos mezclados estereoquímicamente.
Se ha demostrado un control estereoquímico efectivo en una transformación sintética desafiante.

Conclusiones:

El catalizador quiral de níquel permite la formación de enlaces carbono-carbono altamente estereoselectivos.
Este método ofrece una poderosa estrategia para sintetizar estereoisómeros individuales a partir de materiales de partida racémicos.
Representa un avance significativo en la síntesis asimétrica y la metodología catalítica.

Más Videos Relacionados

Highly 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

Highly 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

A Microwave-Assisted Direct Heteroarylation of Ketones Using Transition Metal Catalysis

A Microwave-Assisted Direct Heteroarylation of Ketones Using Transition Metal Catalysis

Published on: February 16, 2020

Videos de Conceptos Relacionados

Stereochemical Effects of Enolization

Stereochemical Effects of Enolization

The chiral α-carbon of the carbonyl compound is the stereocenter of the molecule. As shown in the figure below, when such a carbonyl compound undergoes racemization under an acidic or basic condition, an achiral enol is formed.

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 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 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.

Reduction of Alkenes: Asymmetric Catalytic Hydrogenation

Reduction of Alkenes: Asymmetric Catalytic Hydrogenation

Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...

SN1 Reaction: Stereochemistry

S_N1 Reaction: Stereochemistry

This lesson provides an in-depth discussion of the stereochemical outcomes in an SN1 reaction.
In the first step of an SN1 reaction, the bond between the electrophilic carbon and the leaving group ionizes to generate the carbocation intermediate. The second step of the mechanism is the nucleophilic attack.
In the formed carbocation, the positively charged carbon is sp2 hybridized with a trigonal planar geometry. As all the three substituents lie on the same plane, a plane of symmetry for the...