Design and Synthesis of Novel Pyrimidine/Hexahydroquinazoline-Fused Pyrazolo[3,4-b]Pyridine Derivatives, Their Biological Evaluation and Docking Studies(#)

Multicomponent reaction protocol has been developed for the synthesis of novel pyrimidine fused pyrazolo[3,4-b]pyridine derivatives (7 a-g) and hexahydroquinazoline fused pyrazolo[3,4-b] pyridine derivatives (8 a-i) starting from 3-amino-5-carbethoxy-6-trifluoromethyl pyrazolo[3,4-b] pyridine 5. All the synthesized compounds were evaluated for antibacterial as well as antifungal activities and compounds 7 f, 8 a, 8 c and 8 d exhibited promising antibacterial activity. In particular, compound 2,4,6-trifluoro substituted pyrimidine fused pyrazolo[3,4-b]pyridine (7 f) showed very good antibacterial activity against the panel of both Gram-positive and -negative bacterial strains. Hexahydroquinazoline fused pyrazolo[3,4-b]pyridine derivatives (8 f-i) also showed promising antifungal activity and broad-spectrum anti-biofilm activity against both Gram-positive and negative bacterial strains. The crystal structure of compound 8 b was solved based on single crystal X-ray diffraction study. Docking studies were performed to identify the interactions of the compounds 7 f with crtM enzyme of Staphylococcus aureus.