Green and chemoselective synthesis of pyrazolo[3,4-e][1,4]thiazepines and evaluation of their anti-infective activities

A green and convenient approach to the synthesis of medicinally valuable pyrazolo[3,4-e][1,4]thiazepines via three-component reaction of appropriate aldehydes, 5-amino-3-methylpyrazole, and α-mercaptocarboxylic acids in water under sonication is described. This new protocol provides, via chemoselective synthesis, a new heptacyclic ring system instead of the expected pentacyclic ring system. Experimental simplicity, good functional group tolerance, excellent yields, short routine, and selectivity without the need of a catalyst are prominent features of this sonocatalyzed procedure. The representative compounds were screened for their in vitro anti-bacterial and anti-tubercular activities.