An eco-friendly Pictet–Spengler approach to pyrrolo- and indolo[1,2-a]quinoxalines using p-dodecylbenzenesulfonic acid as an efficient Br?nsted acid catalyst?

RSC Advances Pub Date: 2015-02-13 DOI: 10.1039/C4RA16651E

Abstract

A facile and environmentally benign Pictet–Spengler strategy for the synthesis of a series of biologically important pyrrolo- and indolo[1,2-a]quinoxalines has been developed by reacting 1-(2-aminophenyl)-pyrrole or 1-(2-aminophenyl)indoles with a wide range of aromatic aldehydes, acetophenones or isatins in ethanol at ambient temperature using p-dodecylbenzenesulfonic acid (p-DBSA) as an efficient Br?nsted acid–surfactant combined catalyst. This methodology was found to be applicable to generate diverse quinoxaline derivatives in fairly good yields under mild reaction conditions.

Graphical abstract: An eco-friendly Pictet–Spengler approach to pyrrolo- and indolo[1,2-a]quinoxalines using p-dodecylbenzenesulfonic acid as an efficient Br?nsted acid catalyst
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