A preparatively convenient method is proposed for the synthesis of new 1-oxo-3,4-dihydro-1H-pyrrolo[2,1-с][1,4]oxazine-8- 4a-e and 4-oxo-4H-pyrrolo[2,1-c][1,4]benzoxazine-3-carboxylic acids 5a-f that is based on the interaction of methyl (2-oxomorpholin-3-ylidene)ethanoates 1a-e and methyl (2-oxo-2H-1,4-benzoxazine-3(4H)-ylidene)ethanoates 2a-f with 2-bromo-1,1-diethoxyethane. Obtained acids were transformed into the corresponding tert-butyl carbamates 6a-e, 7a-f and N-alkyl(aryl)carboxamides 11a-i, 12a-d. By treating tert-butyl carbamates 6a-e, 7a-f with hydrogen chloride, 8-amino-3,4-dihydro-1H-pyrrolo[2,1-c][1,4]oxazin-1-ones 8a-e and 3-amino-4H-pyrrolo[2,1-c][1,4]benzoxazin-4-ones 9a-f were obtained. By acylation of amines 8a-e, 9a-f with acetic anhydride, benzoyl chloride, methanesulfonyl chloride, and p-toluenesulfonyl chloride, corresponding N-acetamides 13a,b, 14, N-benzamides 15, 16, N-methanesulfonamides 17, 18, and N-p-toluenesulfonamides 19, 20 were synthesized. In total, 30 new derivatives of 1-oxo-3,4-dihydro-1H-pyrrolo[2,1-c][1,4]oxazinones and 27 new 4-oxo-4H-pyrrolo[2,1-c][1,4]benzoxazinones were obtained.

A number of 3-aryl-5,6-dihydroimidazo[2,1-b][1,3]thiazoles were synthesized by cyclocondensation of imidazolidine-2-thione with phenacyl bromides, and their antimicrobial and antioxidant activity was evaluated. Bioscreening confirmed the moderate antibacterial activity against the reference strains of bacteria Staphylococcus aureus, Escherichia coli and Proteus vulgaris and excellent antifungal activity against Candida albicans. It was found that 3-(4-chlorophenyl)-5,6-dihydroimidazo[2,1-b]thiazole 4h (MIC = 15.625 μg/ml) has twice the antifungal effect compared to the control drug Furacilin. The study of the antioxidant activity of the synthesized compounds proved their ability to inhibit 60–97% of DPPH radicals. The best antiradical effect was found for 4-(5,6-dihydroimidazo[2,1-b]thiazol-3-yl)phenol 4e (I = 97%). A probable mechanism of its action was proposed involving the formation of a radical cation by the SET process. For the most active antioxidants 4e-g, reactivity and electrostatic surface potential were evaluated using the DFT method, and molecular docking was studied on the human peroxiredoxin 5 protein model.

Here derivatives of imidazo[2,1-b][1,3]thiazines are attractive objects for organic and medicinal chemists. In the present work chemoselective conditions for oxidation of the sulfur atom in the 6-(2-pyridinyloxy)substituted (benzo)imidazo[2,1-b][1,3]thiazines to the corresponding sulfoxides were proposed and their synthesis was performed. Synthesized sulfoxides exist in the diastereomeric mixture and individual diastereomers 2a-e and 3a-e were obtained using a chromatographic technique. The structure of compounds 2a-e and 3a-e were characterized using ¹H, ¹³C NMR, LC-MS spectra, and X-ray analysis for derivative 2b. The anti-inflammatory activity screening in vivo was performed using the carrageenan model of inflammatory paw edema in white rats for all the diastereomeric mixtures and individual diastereomers. Diastereomer 2c possessed an anti-inflammatory effect with an inflammation inhibition index of 46.1% which was equal to the activity of the reference drug diclofenac sodium.