Synthesis, Configuration, and Antimicrobial Properties of Novel Substituted and Cyclized '2′,3″-Thiazachalcones'

Nine new thiazachalcone‐based drugs, compounds 1–9, were prepared and fully characterized. The configurations of the photochemical‐dimerization products 7–9 were rationalized by semi‐empirical calculations. Both the experimental data and the theoretical calculations showed that the δ‐truxinic acid type dimer is the most stable isomer of all. All compounds were tested for their antibacterial and antifungal activities. The N‐alkylated congeners 4–6 showed strong antimicrobial activities against various bacteria and a yeast‐like fungus. The MIC and MBC values were as low as 0.1 μg/ml. All the compounds were active against the Gram‐positive bacterium Staphylococcus aureus.