Synthesis, identification and antimicrobial activity of substituted thiazolines and 1,3,4-thiadiazines from dehydroacetic acid

The reaction of thiosemicarbazones with various α-chloroketones in the presence of anhydrous NaOAc led to 4-thiazolines <b>5</b>, <b>7</b> or 1,3,4-thiadiazines <b>11</b> in good yields. Structure elucidation was carried out by ¹H, ¹³C, and FT-IR spectroscopy. The purity of these new products was confirmed by HRMS. A possible mechanism for the formation of <b>5</b>, <b>7</b>, and <b>11</b> was discussed. All the synthesized novel 4-thiazoline and 1,3,4-thiadiazine derivatives were evaluated <i>in vitro</i> for their antibacterial and antifungal activities against six pathogenic bacteria and a strain of yeast: <i>Escherichia coli</i> ATCC 25992, <i>Pseudomonas aeruginosa</i> ATCC 27852, <i>Staphylococcus aureus</i> ATCC 25923 <i>methicillin-resistant</i>, <i>Staphylococcus aureus</i> ATCC 43300 <i>methicillin-sensitive</i>, <i>Micrococcus luteus</i> ATCC 4698 <i>Enterococcus faecalis</i> ATCC 29212 and <i>Candida albicans</i> IPA (200). Some compounds exhibited relatively significant antibacterial and antifungal activities.