Pyrazolopyrimidine‐based scaffolds as antibacterial agents: Synthetic strategies, reactions, and in vitro biological evaluation

Pyrazolopyrimidine scaffold is one of the most favored heterocycles in drug discovery. Herein, a convenient and efficient protocol for the assembly of the hitherto unreported 4‐(4‐(dimethylamino)phenyl)‐3‐methyl‐4,5‐dihydro‐1H‐pyrazolo[3,4‐d]pyrimidine‐6‐thiol (1) was disclosed. This approach comprises arylidene formation via a Knoevenagel condensation reaction between commercially available 3‐methyl‐1H‐pyrazol‐5(4H)‐one and 4‐(dimethylamino) benzaldehyde followed by a subsequent cyclization reaction with thiourea. Thereafter, a series of assorted fused and attached heterocycles originating from pyrazolo[3,4‐d]pyrimidine derivative 1 was synthesized. Finally, the antibacterial activity of the novel assembled heterocycles was in vitro evaluated against diversified Gram‐negative and Gram‐positive bacteria. Various analytical and spectroscopic methods were utilized to confirm the proposed structures of the newly‐synthesized compounds.