Design, Synthesis, and Biological Activity of New Thiazolidine-4-One Derived from Symmetrical 4-Amino-1,2,4-Triazole

Thiazolidine-4-one derivatives (IV)a,b containing 1,2,4-triazole rings linked to 3,4,5-trihydroxyphenyl moiety were designed, synthesized, and biological evaluated for the antibacterial/antifungal activities. These derivatives (IV)a,b were achieved from many sequence reactions. A multi-step reaction protocol was used that began with the first step involved a new and very fast one-pot solventless greener microwave-assisted method of synthesis galloyl hydrazide (I) from gallic acid and hydrazine hydrate. The galloyl hydrazide (I) was used as the starting materials for synthesizing new 5,5'-(4-amino-4H-1,2,4-triazole-3,5-diyl) bis (benzene-1,2,3-triol) (II) via a reflux cyclization process of galloyl hydrazide in DMSO. On the other hand, new Schiff base (III)a,b was prepared via condensation reaction of the symmetrical 4-amino-1,2,4-triazole compound (II) and substituted aromatic aldehyde in ethanol. Finally, the treatment of schiff bases (III)a,b was done with thioglycollic acid in refluxing dioxin by using zinc chloride (II) to afford the target thiazolidine-4-one derivatives (IV)a,b. The structure identification of the newly compounds (I-IVa,b) was elucidated by FT-IR,1H-NMR, and 13C-NMR. The new synthetic derivatives were subjected for antibacterial/ antifungal activity by using two type of Gram-positive and Gram-negative bacteria also test it against to Candida albicans as a fungi sample.