Synthesis of 4,8-dihydro-1H-pyrazolo[3,4-e][1,4]thiazepin-7(6H)-one derivatives by solid acid-catalyzed multi-component reaction in water

Abstract

A solid acid functionalized with polyvinyl alcohol and hydroxyethylsulfuric acid is found to efficiently catalyze the one-pot three-component condensation of substituent-pyrazoles, aldehydes, and thioglycollic acid to afford a wide range of 4,8-dihydro-1H-pyrazolo[3,4-e][1,4]thiazepin-7(6H)-one derivatives with good to excellent yields. The use of a recyclable heterogeneous solid acid catalyst makes this procedure mild, simple, efficient, and sustainable.