First synthesis and biological evaluation of indeno[2,1-e]pyrazolo[3,4-b]pyrazin-5-one and related derivatives

The synthesis of indeno[2,1-e]pyrazolo[3,4-b]pyrazin-5-one was achieved by intramolecular Friedel–Crafts reaction of the acid chloride 3-methyl-1,6-diphenyl-1H-pyrazolo[3,4-b] pyrazine-5-carboxylic acid chloride (4) using AlCl3 in boiling CS2. Compound 4 proved to be a versatile compound for the synthesis of several Indenopyrazolopyrazinone derivatives. The antibacterial and antifungal activities of selected derivatives were evaluated.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A new heterocyclic system indeno[2,1-e]pyrazolo[3,4-b]pyrazine was synthesized. ► Several derivatives of this heterocyclic system have been prepared. ► Selected derivatives were screened for their antibacterial and antifungal activities. ► Other utilities of the compounds prepared are under investigation.