Solar radiation-assisted one-pot synthesis of 3-alkylated indoles under catalyst-free conditions

Abstract

Solar radiation-assisted green approach was developed for the chemoselective synthesis of 3-alkylated indoles via Yonemitsu-type condensation under catalyst-free conditions. The desired products were formed by one-pot three-component reaction of indole, aromatic aldehydes, and β-dicarbonyl compounds in polyethylene glycol-400 (PEG-400). The scope and generality of the presented approach were extended by various aromatic aldehydes and CH activated compounds. Using non-volatile solvent and renewable energy resources, absence of any catalyst, energy conservation, and the selective production of heterodimer product instead of homodimer adducts such as bisindole or xanthine, increase the economic and environmental effectiveness of the present protocol.