Copper‐Catalyzed One‐Pot Synthesis of Pyrrolo[1,2‐a]quinoxaline Derivatives from 1‐(2‐Aminophenyl)‐pyrroles and Aldehydes

Abstract

A facile and highly efficient copper-catalyzed strategy has been developed for the synthesis of pyrrolo[1,2-a]quinoxalines from 1-(2-aminophenyl)-pyrroles and aldehydes at room temperature. This reaction proceeds via imine formation, cyclisation, and oxidation in one-pot. This strategy provides a facile and rapid access to pyrrolo[1,2-a]quinoxalines in good to high yields under mild conditions. This process has several advantages, such as simple reaction procedure, readily available starting materials, low catalyst loading, easy product isolation, broad substrate scope, high functional group tolerance, and gram-scale synthesis.[a] T. Figure 1. Biologically active pyrrolo[1,2-a]quinoxalines and their derivatives.

Three-Component Synthesis of Pyrrolo/indolo[1,2-a]quinoxalines Substituted with o-Biphenylester/N-arylcarbamate/N-arylurea: A Domino Approach Involving Spirocyclic Ring Opening

“…At present, C4-substituted pyrrolo/indolo­[1,2- a ]­quinoxalines are actively involved in various biomedicinal applications such as central 5-HT 3 receptor antagonists, D-loop activity of RAD51 inhibitors, antileishmanial, antimalarial, anticancer, and anti-HIV activities. Usually, a two-component condensation or oxidative cyclization reaction of N -(2-aminophenyl)­pyrroles/indoles and a variety of carbonyl equivalents including aromatic aldehydes, aryl ketones, aryl acetic acids, pinacols, α-amino acids, benzyl amines, benzyl halides, styrenes, phenylacetylenes, dimethyl sulfoxide, α-carbonyl sulfonium ylide, and alkylboronic acids efficaciously constructs various C4-substituted pyrrolo/indolo­[1,2- a ]­quinoxalines. In 2015, Chen Ma et al reported p -TsOH-catalyzed unusual C–C bond cleavage of 1,3-diketones and β-keto esters to produce a series of 4-aryl/alkylpyrrolo/indolo­[1,2- a ]­quinoxalines (Scheme a) .…”

Acetic Acid Catalysed One-Pot Synthesis of Pyrrolo[1,2-a]quinoxaline Derivatives

“…19 Recently, Krishna reported a one-pot copper-catalysed synthesis of pyrrolo[1,2-a]quinoxalines from 1-(2-aminophenyl)pyrroles and aldehydes. 20 These multistep syntheses have led to moderate yields and, in most cases, require the use of toxic reagents. Therefore, it is highly desirable to develop an efficient, nontoxic and convenient approach for the synthesis of 4-substituted pyrroloquinoxalines.…”

“…Infrared spectra were recorded on an Agilent Technologies Cary 630 FT-IR spectrometer.All of the synthesised pyrrolo[1,2-a]quinoxaline derivatives were characterised and are in good agreement with those reported in the literature. [4][5][6][7][8][9][10] The spectral data of the novel pyrrolo[1,2-a]quinoxalines are shown from S11 onwards.…”