Silica supported phosphotungstic acid catalyzed one pot efficient synthesis of pyrazolopyranopyrimidine derivatives”

Abstract

A simple highly efficient method for synthesis of pyrazolopyranopyrimidine derivative has been developed. We have prepared heterogeneous silica supported phosphotungstic acid catalyst and characterized completely by different spectroscopic and analytical techniques. After successful characterization of catalyst, it was employed in the synthesis of pyrazolopyranopyrimidine derivatives from barbituric acid, 3-methyl-5-pyrazolone and substituted aryl aldehydes under optimized reaction conditions. Results showed that, silica supported phosphotungstic acid catalyst much more effective and selective catalyst for the synthesis of pyrazolopyranopyrimidine derivatives under greener conditions. Key advantage of this method was easy work up, recyclability of catalyst up to five cycles, highly efficient synthesis of eleven derivatives of pyrazolopyranopyrimidines with 96–88 % isolated yield with maximum purity.