Convenient Synthesis and Biological Activity of Mono and Diacyl 2,5-Dimercapto-1,3,4-thiadiazole Derivatives

New derivatives of 2,5-dimercapto-1,3,4-thiadiazole substituted both at one or two exocyclic sulfur atoms with a series of aroyl or ethoxycarbonyl groups were synthesized in reactions of 2,5-dimercapto-1,3,4-thiadiazole salts with appropriate acid chlorides or ethyl chloroformate in mild conditions. The products were characterized by spectroscopy (¹H NMR, ¹³C NMR, IR, and HRMS). Some from the synthesized compounds were screened in vitro and in vivo for antibacterial and antifungal activities against a panel of reference strains of microorganisms. The study revealed that ethyl S-(5-mercapto-1,3,4-thiadiazol-2-yl) carbonothioate seems to be the most active and versatile compound against Gram-positive bacteria, Gram-negative bacteria, and plant pathogenic fungi.