Synthesis and determination of antimicrobial and antioxidant activities of imidazo[2,1-b][1,3,4]thiadiazole derivative hybrid compounds and some substituted aromatic schiff bases

In the first part of the study, the syntjhesis of imidazo[2,1-b][1,3,4]thiadiazole (ITD) (46a and 46b) ring core fused starting from 3,4-dihydroxybenzoic acid was carried out in two different series. The corresponding Mannich bases (compounds 47 - 50) were synthesized in the presence of InCl3 catalyst using different secondary amines. Norfloxacin and Ciprofloxacin compounds, which are fluoroquinolone drugs, are also included in the synthesized Mannich bases (47a, 47b, 48a and 48b) as pharmacophores. In addition, morpholine, thiomorpholine, phenylpiperazine, 1-(2-pyrimidyl)piperazine and indole amines were used to incorporate groups into the structure with formaldehyde at the ITD C5 position (49a-49e and 50a-50e). All the synthesized compounds were analyzed for their antimicrobial activities compared to standard drugs against some test microorganisms. In addition, antioxidant capacities were examined with FRAB and DPPH methods. In the second part, starting from picric acid (62) with nitro groups in its structure, the acetohydrazide derivative (64) compound, which will be an intermediate starting material for the acquisition of Schiff bases (65a-65e), was carried out by treatment with ethylbromoacetate and hydrazinhydrate, respectively. Then, Schiff bases were obtained with different substituted aromatic aldehydes (salicylaldehyde, 5-methoxysalicylaldehyde, vanillin, anisaldehyde and 2,4,6-trihydroxybenzaldehyde) in the target product. The structures of all synthesized compounds were characterized by FT-IR, 1H-NMR, 13C-NMR ve LC-MS spectroscopic methods.