Video Experimental Relacionado

Updated: May 23, 2026

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones

Published on: February 7, 2019

El paradigma de Curtin-Hammett para el estereocontrol en la organocatálisis por medio de catalizadores de éter de

Jordi Burés¹, Alan Armstrong, Donna G Blackmond

¹Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, USA.

Journal of the American Chemical Society

|March 29, 2012

Resumen

Los catalizadores de éter de diarilprolinol controlan la estereoquímica a través de intermediarios aguas abajo, no solo los estados de transición iniciales. Este escenario de Curtin-Hammett impacta la selectividad en las reacciones de aldehído, ofreciendo ideas para el diseño de catalizadores.

Área de la Ciencia:

Química orgánica es la química orgánica.
La catálisis de la catálisis.
Mecanismos de reacción Mecanismos de reacción

Sus antecedentes:

Los catalizadores de éter de diarilprolinol son efectivos en la síntesis asimétrica.
Comprender el control estereoquímico es crucial para el desarrollo de catalizadores.

Objetivo del estudio:

Para dilucidar el mecanismo de las reacciones catalizadas por éter de diarilprolinol.
Investigar los factores que determinan los resultados estereoquímicos.

Principales métodos:

Estudio mecanicista detallado de las reacciones de adición conjugada y cloración α.
Análisis de los factores cinéticos y termodinámicos.

Principales resultados:

El resultado estereoquímico está dictado por los intermediarios diastereoméricos aguas abajo, no el estado de transición inicial de ataque de enamina.
Un escenario de Curtin-Hammett influye en la selectividad, potencialmente mejorando o erosionando los resultados predichos.
Este fenómeno puede ser general para los catalizadores de pirrolidina que carecen de protones ácidos.

Conclusiones:

El diseño del catalizador y la reacción debe considerar los intermediarios aguas abajo para optimizar la estereoselectividad.
El mecanismo propuesto ofrece una nueva perspectiva sobre el control estereoquímico en la organocatálisis.

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

Retropinacol/Cross-pinacol Coupling Reactions - A Catalytic Access to 1,2-Unsymmetrical Diols

Retropinacol/Cross-pinacol Coupling Reactions - A Catalytic Access to 1,2-Unsymmetrical Diols

Published on: April 4, 2014

Videos de Conceptos Relacionados

Thermal Electrocyclic Reactions: Stereochemistry

Thermal Electrocyclic Reactions: Stereochemistry

The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.

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...

Regioselectivity and Stereochemistry of Hydroboration

Regioselectivity and Stereochemistry of Hydroboration

A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.

Photochemical Electrocyclic Reactions: Stereochemistry

Photochemical Electrocyclic Reactions: Stereochemistry

The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation

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.

Diels–Alder Reaction Forming Cyclic Products: Stereochemistry

Diels–Alder Reaction Forming Cyclic Products: Stereochemistry

The Diels–Alder reaction is one of the robust methods for synthesizing unsaturated six-membered rings. The reaction involves a concerted cyclic movement of six π electrons: four π electrons from the diene and two π electrons from the dienophile.