Video Experimental Relacionado
Updated: May 25, 2026
10:17
Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
Construcción diastereoselectiva de sin-1,3-dioxanos a través de una reacción de adición de dos componentes de
P Andrew Evans1, Aleksandr Grisin, Michael J Lawler
1Department of Chemistry, The University of Liverpool, Crown Street, Liverpool L69 7ZD, United Kingdom. Andrew.Evans@liverpool.ac.uk
Journal of the American Chemical Society
|February 3, 2012
Resumen
Este estudio introduce una simple y eficiente reacción catalizada por bismuto para crear sin-1,3-dioxanos. El método forma directamente grupos valiosos de retiro de electrones, simplificando las vías sintéticas.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La catálisis es la catálisis.
- Metodología sintética de la metodología sintética.
Sus antecedentes:
- La síntesis estereoselectiva de moléculas orgánicas complejas es crucial en el descubrimiento de fármacos y la ciencia de los materiales.
- El desarrollo de métodos catalíticos eficientes para la construcción de compuestos heterocíclicos como los 1,3-dioxanos sigue siendo un área activa de investigación.
- La catálisis de bismuto ofrece una alternativa más ecológica y a menudo más selectiva a los catalizadores tradicionales de metales pesados.
Objetivo del estudio:
- Desarrollar un método novedoso, altamente eficiente y estereoselectivo para sintetizar syn-1,3-dioxanes.
- Para explorar la utilidad de la catálisis del bismuto en una reacción de adición de dos componentes hemiacetal/oxa-conjugado.
- Para demostrar la introducción directa de grupos de retirada de electrones sin requerir ajustes del estado de oxidación.
Principales métodos:
- Utilizando un catalizador de bismuto para mediar la reacción entre los aldehídos/cetonas β-insaturados y los aldehídos de alquilo.
- Empleando una estrategia de reacción de dos componentes que implica la formación de hemiacetal seguido de la adición de oxa-conjugado.
- Caracterización de los productos de sin-1,3-dioxano resultantes utilizando técnicas espectroscópicas estándar.
Principales resultados:
- Se logró una síntesis altamente eficiente y estereoselectiva de syn-1,3-dioxanes.
- Demostró la simplicidad operativa del protocolo desarrollado.
- Accede con éxito a moléculas con grupos de retirada de electrones directamente, evitando procesos de oxidación en varios pasos.
Conclusiones:
- La reacción mediada por bismuto proporciona una ruta poderosa y directa a valiosos derivados de syn-1,3-dioxano.
- Esta metodología ofrece ventajas significativas en términos de eficiencia, estereoselectividad y convergencia sintética.
- La capacidad del protocolo para instalar directamente grupos funcionales agiliza la síntesis de moléculas complejas.
![Solid-phase Synthesis of [4.4] Spirocyclic Oximes](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F58508.jpg&w=3840&q=50)
Videos de Conceptos Relacionados
02:44Oxidation 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.
02:04Oxidation 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.
![[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F12417.jpg&w=3840&q=75)
01:16[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
03:00Preparation of Epoxides
Overview
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of peroxy acids to...
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of peroxy acids to...
01:28Diels–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.
02:36Regioselectivity 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.
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.