New 1,3,4-bisthiadiazolines: Synthesis, characterization and antimicrobial evaluations

The bisthiadiazolines 4a–4g have been synthesized in good yields from the cyclization reactions of bisthiosemicarbazones 3a–3g with acetic anhydride. The condensation reaction of dibenzaldehydes 2a–2g with thiosemicarbazide in alcoholic medium provided 3a–3g and former were obtained from the O-alkylation of 3-hydroxybenzaldehyde with suitable 1,ω-dibromoalkanes under alkaline conditions in the presence of dry EtOH/DMF. The intermediates 3a–3g and bishetrocyclics 4a–4g were also screened for their in vitro antimicrobial activities against seven bacterial strains (Klubsellia pneumoniae, Pseudomonas aeruginosa, Escherichia coli, Straphylococcus aureus, Bacillius subtilis, Pseudomonas fluorescens and Streptoccus pyrogens) and five fungi strains (Aspergillius janus, Pencillium glabrum, Fusarium oxysporum, Aspergillus sclerotiorum, Aspergillus niger). The compounds 3f, 3g, 4f & 4g were found to be significantly active against the tested microorganisms.

Graphical abstractNew bisthiadiazolines built around the aliphatic chains of varying length has been synthesized. The structures of the intermediates and final bisheterocyclics were determined from the rigorous analysis of their various spectroscopic data. The compounds 3f, 3g, 4f & 4g exhibited significant activity against the tested microorganisms.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The aliphatic chains linked new bisthiadiazolines have been synthesized. ► These compounds have been prepared from the cyclization reactions of the bisthiosemicarbazones with acetic anhydride. ► All the products have been characterized by using various spectroscopic techniques. ► The antimicrobial activities of these compounds have also been studied.