Video Experimental Relacionado

Updated: Jul 12, 2026

Sequence-specific Labeling of Nucleic Acids and Proteins with Methyltransferases and Cofactor Analogues

Sequence-specific Labeling of Nucleic Acids and Proteins with Methyltransferases and Cofactor Analogues

Published on: November 22, 2014

Síntesis totales enantioselectivas de manzamina a y alcaloides relacionados

John M Humphrey¹, Yusheng Liao, Amjad Ali

¹Department of Chemistry and Biochemistry, The University of Texas, Austin, Texas 78712, USA.

Journal of the American Chemical Society

|July 18, 2002

Resumen

Los investigadores desarrollaron una nueva reacción de dominó Stille/Diels-Alder para sintetizar alcaloides de manzamina. Esta estrategia permitió la construcción eficiente y enantioselectiva de los intermediarios clave, lo que condujo a la síntesis total de ircinol A, ircinal A y manzamina A.

Área de la Ciencia:

Química orgánica es la química orgánica.
Síntesis total de las respuestas.
Productos Naturales Química Productos Naturales

Sus antecedentes:

Los alcaloides de manzamina son una clase compleja de productos naturales con actividades biológicas significativas.
Los esfuerzos sintéticos anteriores se han visto obstaculizados por las intrincadas estructuras de estos alcaloides.

Objetivo del estudio:

Establecer el alcance y las limitaciones de las cicloadiciones intramoleculares [4 + 2] para la síntesis de precursores alcaloides de manzamina.
Para lograr la síntesis total enantioselectiva de ircinol A, ircinal A y manzamina A.

Principales métodos:

Estudios modelo que incluyen cicloadiciones intramoleculares [4 + 2] de ureas vinílogas N-aciladas con sustratos triénicos.
Una estrategia convergente con una nueva reacción de dominó Stille/Diels-Alder para construir el núcleo de anillo ABC tricíclico.
Dos reacciones de metatesis de cierre de anillo para formar los anillos de 13 y 8 miembros.

Principales resultados:

Demostrado que la geometría de enlace doble interno y los grupos de retirada de electrones son cruciales para las cicloadiciones fáciles y estereoselectivas.
Se sintetizó con éxito un intermediario tricíclico clave (60) a partir de un dihidropirrol quiral (58) en un solo paso.
Completó la síntesis total de ircinol A (75), ircinal A (5) y manzamina A (1) de una manera concisa.

Conclusiones:

La reacción de dominó Stille/Diels-Alder desarrollada es una herramienta poderosa para construir el núcleo alcaloide de manzamina.
La vía sintética es eficiente, enantioselectiva y susceptible a la síntesis de productos naturales relacionados.
Este trabajo proporciona una plataforma valiosa para una mayor exploración de la química de los alcaloides de manzamina.

Más Videos Relacionados

Hydrolysis of a Ni-Schiff-Base Complex Using Conditions Suitable for Retention of Acid-labile Protecting Groups

Hydrolysis of a Ni-Schiff-Base Complex Using Conditions Suitable for Retention of Acid-labile Protecting Groups

Published on: April 6, 2017

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

Videos de Conceptos Relacionados

Aldehydes and Ketones with Amines: Imine and Enamine Formation Overview

Aldehydes and Ketones with Amines: Imine and Enamine Formation Overview

Primary amines react with carbonyl compounds—aldehydes and ketones—to generate imines. Imines consist of a C=N double bond and are named Schiff bases after its discoverer—the German chemist Hugo Schiff. On the other hand, secondary amines react with carbonyl compounds to give enamines. In enamines, the presence of a C=C double bond adjacent to the nitrogen atom leads to the delocalization of the lone pair.

Conjugate Addition of Enolates: Michael Addition

Conjugate Addition of Enolates: Michael Addition

The attack of a nucleophile at the β carbon of an α,β-unsaturated carbonyl compound is called conjugate addition. Conjugate addition reactions of active methylene compounds, such as β-diketones, β-keto esters, β-keto nitriles, and α-nitro ketones, are called Michael addition reactions.

meta-Directing Deactivators: –NO2, –CN, –CHO, –&NoBreak;CO2R, –COR, –CO2H

meta-Directing Deactivators: –NO₂, –CN, –CHO, –⁠CO₂R, –COR, –CO₂H

All meta-directing substituents are deactivating groups. These substituents withdraw electrons from the aromatic ring, making the ring less reactive toward electrophilic substitution. For example, the nitration of nitrobenzene is 100,000 times slower than that of benzene because of the deactivating effect of the nitro group. The first step in an electrophilic aromatic substitution is the addition of an electrophile to form a resonance-stabilized carbocation. The energy diagrams for the...

Preparation of Amines: Reduction of Oximes and Nitro Compounds

Preparation of Amines: Reduction of Oximes and Nitro Compounds

Oximes can be reduced to primary amines using catalytic hydrogenation, hydride reduction, or sodium metal reduction. The reduction of aliphatic and aromatic nitro compounds to primary amines takes place by either catalytic hydrogenation or by using active metals like Fe, Zn, and Sn in the presence of an acid.
Though catalytic hydrogenation can reduce nitrobenzenes, the reduction is nonselective in the presence of other functional groups. For instance, if nitrobenzene contains an aldehyde group,...

Aldol Condensation with β-Diesters: Knoevenagel Condensation

Aldol Condensation with β-Diesters: Knoevenagel Condensation

The Knoevenagel condensation is an aldol-type reaction involving the condensation of aldehydes or ketones with active methylene compounds such as β-diesters to produce substituted olefins.

Nitrosation of Enols

Nitrosation of Enols

The nitrosation reaction is one of the methods of preparing 1,2-diketones. The enol tautomer of the starting ketone reacts with sodium nitrite in hydrochloric acid, generating the 1,2-diketone after hydrolysis.