Video Experimental Relacionado

Updated: Jun 21, 2026

A Direct, Regioselective and Atom-Economical Synthesis of 3-Aroyl-N-hydroxy-5-nitroindoles by Cycloaddition of 4-Nitronitrosobenzene with Alkynones

A Direct, Regioselective and Atom-Economical Synthesis of 3-Aroyl-N-hydroxy-5-nitroindoles by Cycloaddition of 4-Nitronitrosobenzene with Alkynones

Published on: January 21, 2020

La alfa-nitroalquilación enantioselectiva del aldehído por medio de la organocatálisis oxidativa

Jonathan E Wilson¹, Anthony D Casarez, David W C MacMillan

¹Merck Center for Catalysis, Princeton University, Princeton, New Jersey 08544, USA.

Journal of the American Chemical Society

|July 25, 2009

Resumen

Los investigadores desarrollaron la primera enantioselectiva organocatalítica alfa-nitroalquilación de aldehídos. Este nuevo método sintetiza eficientemente los beta-nitroaldehídos y los valiosos beta-aminoácidos.

Área de la Ciencia:

Química orgánica es la química orgánica.
Catalización asimétrica por catálisis asimétrica.

Sus antecedentes:

La síntesis enantioselectiva es crucial para los productos farmacéuticos.
La organocatálisis ofrece un enfoque libre de metales para la síntesis de moléculas quirales.

Objetivo del estudio:

Desarrollar la primera enantioselectiva organocatalítica alfa-nitroalquilación de aldehídos.
Para sintetizar los nitroaldehídos sintéticos y anti-beta.
Para establecer una ruta para los ácidos amino-beta alfa quirales, beta-disubstituidos.

Principales métodos:

Acoplamiento oxidativo organocatalítico de los intermediarios de enamina con los nitronatos de sililo.
Desarrollo de dos métodos distintos para la síntesis de nitroaldehído sintético y anti-beta.
Un procedimiento de tres pasos para la síntesis de beta-aminoácidos.

Principales resultados:

Logro exitoso de la primera enantioselectiva organocatalítica alfa-nitroalquilación de aldehídos.
Generación de isómeros de nitroaldehído sin y anti-beta.
Demostración de una vía mecanicista controlada por el grupo sililo.
Síntesis eficiente de ácidos beta-aminoácidos sin y anti-alfa, beta-disubstituidos.

Conclusiones:

Se ha establecido un nuevo y versátil método organocatalítico para la alfa-nitroalquilación enantioselectiva.
La metodología proporciona acceso a los beta-nitroaldehídos y los beta-aminoácidos definidos estereocímicamente.
Se obtuvieron conocimientos mecánicos sobre la influencia del grupo sililo en la estereoselectividad.

Más Videos Relacionados

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

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

α-Alkylation of Ketones via Enolate Ions

α-Alkylation of Ketones via Enolate Ions

Ketones with α protons are deprotonated by strong bases like lithium diisopropylamide (LDA) to form enolate ions. The anion is stabilized by resonance, and its hybrid structure exhibits negative charges on the carbonyl oxygen and the α carbon. This ambident nucleophile can attack an electrophile via two possible sites: the carbonyl oxygen, known as O-attack, or the α carbon, known as C-attack. The nucleophilic attack via the carbanionic site is preferred. This is due to the strong interaction...

Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide

Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide

Alkenes are converted to 1,2-diols or glycols through a process called dihydroxylation. It involves the addition of two hydroxyl groups across the double bond with two different stereochemical approaches, namely anti and syn. Dihydroxylation using osmium tetroxide progresses with syn stereochemistry.

Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids

Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids

Diols are compounds with two hydroxyl groups. In addition to syn dihydroxylation, diols can also be synthesized through the process of anti dihydroxylation. The process involves treating an alkene with a peroxycarboxylic acid to form an epoxide. Epoxides are highly strained three-membered rings with oxygen and two carbons occupying the corners of an equilateral triangle. This step is followed by ring-opening of the epoxide in the presence of an aqueous acid to give a trans diol.

Oxidations of Aldehydes and Ketones to Carboxylic Acids

Oxidations of Aldehydes and Ketones to Carboxylic Acids

Oxidation of aldehydes and ketones results in the formation of carboxylic acids. Aldehydes, bearing hydrogen next to the carbonyl group, are easily oxidized compared to ketones. This is because an aldehydic proton can easily be abstracted during oxidation.
Aldehydes readily undergo oxidation in strong oxidizing agents such as potassium permanganate and chromic acid. The oxidation can also be carried out using mild oxidizing agents such as silver oxide. In fact, aldehydes can be easily oxidized...

Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation

Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation

Introduction
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.

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...