SYNTHESIS AND ANTIOXIDANT ACTIVITY OF 5-CHLORO-2-METHYL-2,3-DIHYDROIMIDAZO[2,1-b][1,3]THIAZOLE-6-CARBALDEHYDE

Imidazothiazoles annelated to the b face have been of particular interest to researchers in recent decades due to their powerful medical and biological potential. Antioxidant therapy of diseases associated with oxidative stress is one of the important areas of modern medicine. That is why this work is devoted to the synthesis of 2-methyl-5-chloro-2,3-dihydroimidazo[2,1-b][1,3]thiazole-6-carbaldehyde and the evaluation of its antioxidant potential. Synthetically available 2-methyl-2,3-dihydroimidazo[2,1-b][1,3]thiazol-5(6H)-one was used as a substrate. The presence of an activated methylene group in its structure makes it very attractive for further structural modification by pharmacoform groups and construction of biologically active compounds. It was found that 2-methylimidazothiazole undergoes a Vilsmeier-Haack reaction during heating with a DMF/POCl3 complex to form a 6-formyl-5-chloro derivative with a yield of 25%. The composition and structure of this chloraldehyde synthesized for the first time was unambiguously confirmed by a set of physicochemical analysis, including elemental analysis, chromato-mass, IR and NMR spectra. Specifically, IR spectrum contains an intense absorption band of valence vibrations of the С=О group at 1684 cm–1. The 1H NMR spectrum is characterized by a formyl group singlet at 9.72 ppm, and the signal of the corresponding carbon atom in the 13C NMR spectrum is recorded at 182.2 ppm. The fact of aromatization of the imidazole ring is confirmed by the shift of the signals of C5 and C6 atoms to the region of 139.4 ppm and 123.2 ppm, respectively. The antioxidant activity was assessed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical inhibition method. Initially, it was experimentally confirmed that the rate of inhibition of radicals by the synthesized compound at a concentration of 5 mM is 54.1%. The next stage of the study showed that the IC50 data is 1.669 mM, vs IC50 = 0.097 mM for ascorbic acid. Therefore, 2-methyl-5-chloro-2,3-dihydroimidazo[2,1-b][1,3]thiazole-6-carbaldehyde is of interest for advanced pharmacological studies and design of promising synthetic antioxidants.