Polyethylene Glycol (PEG-400): A Green Reaction Medium for One-Pot, Three Component Synthesis of 3-Substituted Indoles under Catalyst Free Conditions

Abstract

A catalyst-free, cost-effective and environmentally friendly protocol for the synthesis of 3-substituted indoles via a one-pot multicomponent condensation reaction of indole, C–H activated acids and aromatic aldehydes in polyethylene glycol 400 (PEG-400) as a reaction medium and reaction promoter has been developed. The most important feature of this protocol is selectivity in the formation of heterodimer products instead of homodimer adducts such as bisindole or xanthine.