This review provides readers with an overview of the main synthetic methodologies for 1,3,4-oxadiazole derivatives, and of their broad spectrum of pharmacological activities as reported over the past twelve years.

Five new 1-(2-(5-nitrofuran-2-yl)-5-(aryl)-1,3,4-oxadiazol-3-(2H)-yl) ethanone compounds 5a–e were synthesized by cyclization of N-acylhydrazones 4a–e with acetic anhydride under reflux conditions. Their structures were fully characterized by IR, ¹H-NMR, and ¹³C-NMR. Furthermore, evaluations of the antibacterial activity of the 1,3,4-oxadiazoles 5a–e and N-acylhydrazones 4a–e showed strong activity against several strains of Staphylococcus aureus, with MICs between 4 μg/mL to 32 μg/mL. In silico studies of the parameters of Lipinski’s Rule of Five, as well as the topological polar surface area (TPSA), absorption percentage (% ABS), drug likeness and drug score indicate that these compounds, especially 4a and 5d, have potential to be new drug candidates.

Two salts of the mesoionic compounds 1,4-diphenyl-5-(5-nitro-2-furanyl)-1,3,4-thiadiazolium-2-thiol chloride (MC-1) and 4-phenyl-5-(5-nitro-2-furanyl)-1,3,4-thiadiazolium-2-phenylamine chloride (MC-2) were synthesized utilizing 1,4-diphenyl-thiosemicarbazide and 5-nitro-2-furoyl chloride as starting materials. Their structures were characterized by IR, ¹H-NMR, ¹³C-NMR and elemental analysis. These compounds were analyzed for their influence on the effectiveness of norfloxacin, tetracycline, and erythromycin (standard antibiotics) against resistant strains of Staphylococcus aureus. MC-1 and MC-2, at sub-inhibitory concentrations of 16 μg/mL, favourably modulated the antibiotic activity of tetracycline by 16- and 32-fold, respectively (MIC), and that of erythromycin by 4-fold.