Video Experimental Relacionado

Updated: Mar 9, 2026

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals

Published on: April 19, 2019

Ciclizaciones radicales desaromatizantes y cascadas de ciclización desencadenadas por la reducción por transferencia

Huan-Ming Huang¹, David J Procter¹

¹School of Chemistry, Oxford Road, University of Manchester , Manchester, M13 9PL, United Kingdom.

Journal of the American Chemical Society

|December 21, 2016

Resumen

Este estudio introduce nuevas ciclizaciones de radicales desaromatizantes utilizando dióxido de samario para crear compuestos espirocíclicos complejos. Estos métodos ofrecen un acceso eficiente a andamios médicamente relevantes con un alto control estereoquímico.

Área de la Ciencia:

Química orgánica
Química sintética
Química medicinal

Sus antecedentes:

Las ciclizaciones radicales son cruciales para construir arquitecturas moleculares complejas.
El desarrollo de nuevos métodos de desaromatización es esencial para acceder a andamios químicos únicos.
Los carbonilos de amida son grupos funcionales comunes pero son precursores radicales difíciles.

Objetivo del estudio:

Desarrollar las primeras ciclizaciones de radicales desaromatizantes que involucran carboniles de amida a través de la transferencia de un solo electrón.
Para sintetizar eficientemente andamios espirocíclicos sin precedentes con múltiples estereocentros.
Explorar la formación selectiva de hemiaminas o enaminas policíclicas.

Principales métodos:

Utilizando dióxido de samario (SmI2) con agua y bromuro de litio (LiBr) como sistema reductor.
Utilizando la transferencia de un solo electrón (SET) para activar carbonilos de tipo amida.
Investigación de las reacciones con diversos sustratos de barbitúricos aromáticos y heteroaromáticos.

Principales resultados:

Se han logrado ciclizaciones y cascadas de radicales desaromatizantes altamente selectivas.
Generó andamios espirocíclicos sin precedentes con hasta cinco estereocentros y alto control diastereo.
Síntesis selectiva demostrada de hemiaminas o enaminas policíclicas bajo condiciones suaves.

Conclusiones:

Estableció una nueva y eficiente ruta sintética para compuestos espirocíclicos complejos.
La metodología desarrollada proporciona acceso a andamios médicamente relevantes.
Los productos son fácilmente susceptibles a una mayor manipulación química.

Más Videos Relacionados

Solid-phase Synthesis of [4.4] Spirocyclic Oximes

Solid-phase Synthesis of [4.4] Spirocyclic Oximes

Published on: February 6, 2019

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

Videos de Conceptos Relacionados

Radical Reactivity: Intramolecular vs Intermolecular

Radical Reactivity: Intramolecular vs Intermolecular

Radical reactions can occur either intermolecularly or intramolecularly. In an intermolecular radical reaction, a nucleophilic radical adds to an electrophilic alkene or vice versa. In such reactions, the radical and generally the alkene, which is also called the radical trap, are two different molecules. Additionally, for such intermolecular reactions to occur, the radical trap must be active, present in an excess concentration, and the radical starting material must have a weak...

Radical Formation: Addition

Radical Formation: Addition

Radicals can be formed by adding a radical to a spin-paired molecule. This is typically observed with unsaturated species, where the addition of a radical across the π bond leads to the production of a new radical by dissolving the π bond. For example, the addition of a Br radical to an alkene yields a carbon-centered radical.
Similar to charge conservation in chemical reactions, spin conservation is implicit for radical reactions. Accordingly, the product formed must possess an...

Radical Reactivity: Overview

Radical Reactivity: Overview

Radicals, the highly reactive species, gain stability by undergoing three different reactions. The first reaction involves a radical-radical coupling, in which a radical combines with another radical, forming a spin‐paired molecule. The second reaction is between a radical and a spin‐paired molecule, generating a new radical and a new spin‐paired molecule. The third reaction is radical decomposition in a unimolecular reaction, forming a new radical and a spin‐paired...

Pericyclic Reactions: Introduction

Pericyclic Reactions: Introduction

Pericyclic reactions are organic reactions that occur via a concerted mechanism without generating any intermediates. The reactions proceed through the movement of electrons in a closed loop to form a cyclic transition state, where rearrangement of the σ and π bonds yields specific products.
Pericyclic reactions can be classified into three categories: electrocyclic reactions, cycloaddition reactions, and sigmatropic rearrangements. Electrocyclic reactions and sigmatropic...

Cycloaddition Reactions: Overview

Cycloaddition Reactions: Overview

Cycloadditions are one of the most valuable and effective synthesis routes to form cyclic compounds. These are concerted pericyclic reactions between two unsaturated compounds resulting in a cyclic product with two new σ bonds formed at the expense of π bonds. The [4 + 2] cycloaddition, known as the Diels–Alder reaction, is the most common. The other example is a [2 + 2] cycloaddition.

Benzene to 1,4-Cyclohexadiene: Birch Reduction Mechanism

Benzene to 1,4-Cyclohexadiene: Birch Reduction Mechanism

Birch reduction uses solvated electrons as reducing agents. The reaction converts benzene to 1,4-cyclohexadiene. The reaction proceeds by the transfer of a single electron to the ring to form a benzene radical anion. This anion is highly basic—it abstracts a proton from the alcohol to form a cyclohexadienyl radical. Another single electron transfer gives the cyclohexadienyl anion. A proton transfer from the alcohol forms 1,4-cyclohexadiene. Since this reduction occurs via radical anion...