Síntesis enantioselectiva de azoniahelicenos por anulación de C-H catalizada por Rh con alquinas

Video Experimental Relacionado

Updated: Nov 24, 2025

Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles

Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles

Published on: August 22, 2018

Qiang Wang¹, Wen-Wen Zhang², Chao Zheng¹

¹State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Lu, Shanghai 200032, China.

Journal of the American Chemical Society

|December 28, 2020

Resumen

Un nuevo método catalizado por rodio permite reacciones de activación y anulación C-H enantioselectivas. Este proceso sintetiza eficientemente azoniahelicenos quirales a partir de derivados de isoquinolina y alquinas con alto rendimiento y enantioselectividad.

Área de la Ciencia:

Química organometálica
Catálisis asimétrica
Síntesis orgánica

Sus antecedentes:

Los azoniahelicenos quirales son motivos estructurales importantes en la química supramolecular y la ciencia de los materiales.
Desarrollar rutas sintéticas eficientes y enantioselectivas para estas moléculas complejas sigue siendo un desafío significativo.

Objetivo del estudio:

Desarrollar una nueva estrategia de activación/cancelación C-H enantioselectiva catalizada por el rodio.
Para sintetizar azoniahelicenos quirales con alto rendimiento y enantioselectividad.

Principales métodos:

Utilizó un complejo quiral CpRh (III) como precursor del catalizador.
Empleó un ácido quiral como co-catalizador.
Investigó las reacciones de anulación directa entre los derivados de 1-arilo isoquinolina y varios alquinos.

Principales resultados:

Logró la síntesis de diversos azoniahelicenos quirales.
Se obtienen excelentes rendimientos (hasta el 99%) y una alta enantioselectividad (hasta el 96% ee).
Las investigaciones mecanicistas indicaron que la escisión de los enlaces C-H podría limitar el volumen de negocios.

Conclusiones:

El proceso catalizado por el rodio desarrollado proporciona una ruta eficiente a los azoniahelicenos enriquecidos enantioméricamente.
Esta metodología ofrece una herramienta valiosa para construir estructuras helicoidales quirales complejas.

Más Videos Relacionados

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

Preparation of Contiguous Bisaziridines for Regioselective Ring-Opening Reactions

Preparation of Contiguous Bisaziridines for Regioselective Ring-Opening Reactions

Published on: July 28, 2022

Videos de Conceptos Relacionados

Preparation of 1° Amines: Azide Synthesis

Preparation of 1° Amines: Azide Synthesis

Direct alkylation of ammonia produces polyalkylated amines, along with a quaternary ammonium salt. To exclusively prepare primary amines, the azide synthesis method can be used.
Azide ions act as good nucleophiles and react with unhindered alkyl halides to form alkyl azides. Alkyl azides do not participate in further nucleophilic substitution reactions, thereby eliminating the chances of polyalkylated products. Alkyl azides are reduced by hydride-based reducing agents, like lithium aluminum...

Preparation of Alkynes: Dehydrohalogenation

Preparation of Alkynes: Dehydrohalogenation

Introduction
Alkynes can be prepared by dehydrohalogenation of vicinal or geminal dihalides in the presence of a strong base like sodium amide in liquid ammonia. The reaction proceeds with the loss of two equivalents of hydrogen halide (HX) via two successive E2 elimination reactions.

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.

Preparation of Alkynes: Alkylation Reaction

Preparation of Alkynes: Alkylation Reaction

Introduction
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.

Electrophilic Addition to Alkynes: Halogenation

Electrophilic Addition to Alkynes: Halogenation

Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.

Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic SN1

Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic S_N1

Treating arylamines with nitrous acid gives aryldiazonium salts that are effective substrates in nucleophilic aromatic substitution reactions. The diazonio group in these salts can be easily displaced by different nucleophiles, yielding a wide variety of substituted benzenes. The leaving group departs as nitrogen gas, and this easy elimination is the driving force for the substitution reaction.
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo,...