Video Experimental Relacionado
Updated: May 28, 2026
08:56
Synthesis of a Borylated Ibuprofen Derivative Through Suzuki Cross-Coupling and Alkene Boracarboxylation Reactions
Published on: November 30, 2022
Generación de un boro-borileno estabilizado con carbenos y su inserción en un enlace C-H
Philipp Bissinger1, Holger Braunschweig, Alexander Damme
1Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
Journal of the American Chemical Society
|October 29, 2011
Resumen
Los investigadores sintetizaron un nuevo boraciclo de cinco miembros utilizando un nuevo adducto de NHC de dihalodiborane ((4) y reducción de KC ((8). Esto probablemente implica la inserción de C-H por un intermediario de boro-borileno estabilizado con NHC.
Área de la Ciencia:
- Química del organoborón Química del organoborón
- Grupo Principal Química.
- Química de los carbenos La química de los carbenos
Sus antecedentes:
- Los carbenos N-heterocíclicos (NHC) son ligandos versátiles en la química del grupo principal.
- Los compuestos de diborano ((4) ofrecen vías de reactividad únicas.
- La estabilización de las especies de boro de baja valencia es un área de investigación activa.
Objetivo del estudio:
- Para sintetizar y caracterizar un nuevo ciclo de boro de cinco miembros.
- Para investigar la reactividad de los añadidos NHC de dihalodiboranos.
- Para dilucidar el mecanismo de la formación del borociclo.
Principales métodos:
- Reacción de un nuevo adducto NHC de un dihalodiborano ((4) con KC ((8).
- Caracterización del producto de boraciclo resultante.
- Estudios mecanicistas para proponer vías de reacción.
Principales resultados:
- Síntesis exitosa de un nuevo borociclo de cinco miembros (compuesto 2).
- La reacción se lleva a cabo a través de la reducción del adducto de dihalodiborano (compuesto 1) por KC (8).
- La evidencia sugiere la participación de un intermediario libre de bóra-borileno estabilizado por NHC.
Conclusiones:
- Se ha establecido una nueva ruta sintética para los boraciclos de cinco miembros.
- El estudio destaca la utilidad de los ligandos NHC en la estabilización de las especies reactivas de boro.
- El mecanismo propuesto que involucra la inserción de C-H ofrece información sobre las interacciones boro-carbeno.
Videos de Conceptos Relacionados
03:08Hydroboration-Oxidation of Alkenes
In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.
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.
02:46Halogenation of Alkenes
Halogenation is the addition of chlorine or bromine across the double bond in an alkene to yield a vicinal dihalide. The reaction occurs in the presence of inert and non-nucleophilic solvents, such as methylene chloride, chloroform, or carbon tetrachloride.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
02:10Carbocations
Carbocations are one of the reaction intermediates formed during several nucleophilic substitutions or elimination reactions. A carbocation is an electron-deficient species with the central carbon atom having six electrons and three bonded atoms. The central carbon in a carbocation is sp2 hybridized with trigonal planar geometry. It has an empty p orbital perpendicular to the plane of the structure that can accept electrons. Thus, carbocations act as strong electrophiles and may react with any...
02:15Preparation of Alcohols via Addition Reactions
Overview
The acid-catalyzed addition of water to the double bond of alkenes is a large-scale industrial method used to synthesize low-molecular-weight alcohols. An acidic atmosphere is required to allow the hydrogen in the water molecule to act as an electrophile and attack the double bond in an alkene. The addition of a proton to the double bond creates a carbocation intermediate. The proton preferentially bonds to the less substituted end of the double bond to create a more stable carbocation...
The acid-catalyzed addition of water to the double bond of alkenes is a large-scale industrial method used to synthesize low-molecular-weight alcohols. An acidic atmosphere is required to allow the hydrogen in the water molecule to act as an electrophile and attack the double bond in an alkene. The addition of a proton to the double bond creates a carbocation intermediate. The proton preferentially bonds to the less substituted end of the double bond to create a more stable carbocation...
02:47Alkynes 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.
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.