Synthesis and Antimicrobial Evaluations of 1,3,4‐Thiadiazoline‐based Bisheterocyclics

The bisthiadiazolines (4a, 4b, 4c, 4d, 4e, 4f, 4g) were synthesized from the cyclization of bisthiosemicarbazones (3a, 3b, 3c, 3d, 3e, 3f, 3g) by refluxing under Ac2O medium. The intermediates were obtained from the reactions of dibenzaldehydes (2a, 2b, 2c, 2d, 2e, 2f, 2g) with thiosemicarbazide by refluxing in the presence of dry EtOH/HCl. The latter were prepared in good yields from the O‐alkylation of 3‐hydroxybenzaldehyde with suitable dibromo derivatives under the alkaline conditions. The structures of prepared compounds were determined from rigorous analysis of their spectral parameters (UV–vis, IR, 1H NMR, 13C NMR and ESI‐MS). The newly prepared compounds were screened for their antimicrobial activity against seven bacterial and five fungi strains using serial tube dilution method.