Synthesis and Antimicrobial Activity Evaluation of Novel 4-Thiazolidinones Containing a Pyrone Moiety

A series of thiosemicarbazones 3a–d and 4-thiazolidinones 5a–d, 7a–d, and 9a–h were synthesized and evaluated for their in vitro antimicrobial activity. Condensation of 3-acetyl-4-hydroxy-6-methyl-2H pyran-2-one1 (dehydroacetic acid) with thiosemicarbazide 2a–d in ethanol at room temperature yielded the thiosemicarbazones 3a–d. These compounds were exploited to synthesize the 4-thiazolidinones 5a–d via their reactions with ethyl 2-bromo propionate4. Derivatives 7a–d were prepared by reaction of the thiosemicarbazones 3a–d with phenyl bromoacetate 6. The 4-thiazolidinones 9a–h were obtained by treatment of compound 3a or 3c with maleimide derivatives 8a–d in refluxing ethanol, under sulfuric acid catalysis. All compounds were screened in vitro for their antibacterial and antifungal activities against five human pathogens microorganisms: Escherichia coli ATCC 25992, Pseudomonas aeruginosa ATCC 27852, Staphylococcus aureus ATCC 43300, Staphylococcus aureus ATCC 25923, and Candida albicans.