Video Experimental Relacionado

Updated: Nov 22, 2025

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

Hidroboración cíclica (alquilo) y (amino) carbónica desoxigenada por ligando con catálisis por cromo: alcance,

Lixing Zhao¹, Chenyang Hu², Xuefeng Cong¹

¹Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China.

Journal of the American Chemical Society

|January 8, 2021

Resumen

Este estudio introduce un nuevo método catalizado por cromo utilizando ligandos cíclicos (alquilo) y (amino) carbónicos (CAAC) para la hidroboración nitro desoxigenativa. Este proceso eficiente sintetiza varios derivados de aminas, incluidos los productos farmacéuticos.

Área de la Ciencia:

Química orgánica
Catálisis
Química medicinal

Sus antecedentes:

Los carbenos N-heterocíclicos (NHC) como ligandos en la catálisis de metales de transición no se han estudiado ampliamente.
El desarrollo de métodos catalíticos eficientes y selectivos para la síntesis de aminas es crucial en la química orgánica.

Objetivo del estudio:

Informar sobre una nueva hidroboración desoxigenativa promovida por ligando de carbeno cíclico (alquilo) (amino) (CAAC) mediante catálisis de cromo.
Establecer una estrategia suave, quimioselectiva y fácil para sintetizar diversos derivados de aminas.

Principales métodos:

Se utilizó un catalizador de cromo rentable con un ligando CAAC.
HBpin utilizado para la hidroboración desoxigenativa de los nitroarenos.
Estudios mecanicistas realizados con cálculos teóricos.

Principales resultados:

Se ha logrado una hidroboración desoxigenativa con nitrógeno de alta eficiencia (hasta 1,8 × 10^6 números de rotación).
Compatibilidad demostrada con varias funcionalidades reducibles y grupos sensibles.
Se han sintetizado con éxito anilina, heteroarilo y derivados de aminas alifáticas.
Mostró las aplicaciones potenciales mediante la preparación de compuestos farmacéuticos.

Conclusiones:

El ligando CAAC juega un papel clave en el ciclo catalítico al facilitar la inversión de la polaridad del hidruro y actuar como una lanzadera H.
Este método ofrece un enfoque de amplio alcance, suave y quimioselectivo para la síntesis de aminas.
La estrategia es muy prometedora para aplicaciones en la química medicinal y la síntesis farmacéutica.

Más Videos Relacionados

A Microwave-Assisted Direct Heteroarylation of Ketones Using Transition Metal Catalysis

A Microwave-Assisted Direct Heteroarylation of Ketones Using Transition Metal Catalysis

Published on: February 16, 2020

Synthesis of Hypervalent Iodonium Alkynyl Triflates for the Application of Generating Cyanocarbenes

Synthesis of Hypervalent Iodonium Alkynyl Triflates for the Application of Generating Cyanocarbenes

Published on: September 8, 2013

Videos de Conceptos Relacionados

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.

Hydroboration-Oxidation of Alkenes

Hydroboration-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.

Regioselectivity and Stereochemistry of Hydroboration

Regioselectivity 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.

Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation

Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation

Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.

ortho–para-Directing Activators: –CH3, –OH, –&NoBreak;NH2, –OCH3

ortho–para-Directing Activators: –CH₃, –OH, –⁠NH₂, –OCH₃

All ortho–para directors, excluding halogens, are activating groups. These groups donate electrons to the ring, making the ring carbons electron-rich. Consequently, the reactivity of the aromatic ring towards electrophilic substitution increases. For instance, the nitration of anisole is about 10,000 times faster than the nitration of benzene. The electron-donating effect of the methoxy group in anisole activates the ortho and para positions on the ring and stabilizes the corresponding...

Alkenes via Reductive Coupling of Aldehydes or Ketones: McMurry Reaction

Alkenes via Reductive Coupling of Aldehydes or Ketones: McMurry Reaction

The radical dimerization of ketones or aldehydes gives vicinal diols through a pinacol coupling reaction. However, the behavior of titanium metals used for the reaction as a source of electrons is unusual. When the reaction is carried out in the presence of titanium, diols can be isolated at low temperatures. Else titanium further reacts with diols, forming alkenes through the McMurry reaction.