Zinc chloride catalyzed multicomponent synthesis of pyrazolopyridocoumarin scaffolds

An efficient synthesis of a series of pyrazolopyridocoumarins is reported by condensation of 4-hydroxycoumarin, benzaldehydes and 1-alkyl-5-amino-pyrazoles in the presence of 10 mol% zinc chloride in ethanol under reflux conditions through one-pot reaction. The significant attraction of this protocol is being a simple procedure, mild reaction condition, and excellent yield. The molecular structure of the compound (4e) is established by single crystal X-ray structure determination. A facile and an efficient protocol for the synthesis of novel pyrazolopyridocoumarins have been developed via a one-pot reaction of 4-hydroxycoumarin, benzaldehydes and 1-alkyl-5-amino-pyrazoles in the presence of zinc chloride in ethanol at reflux temperature. The present approach offers the advantages of simple methodology, high atom-economy, mild conditions, short reaction times, low environmental impact and high yield. The molecular structure of the compound (4e) is established by single crystal X-ray structure determination.