An efficient approach to the synthesis of 7-thioxosubstituted [1,3]thiazolo[3,2-c]pyrimidines and evaluation of their antimicrobial and antioxidant activities

Abstract

A preparatively convenient one-pot method for the synthesis of new 7-thioxo[1,3]thiazolo[3,2-c]pyrimidine derivatives 3a–3l by the cyclocondensation of 5-methyl(1,3-thiazolidin-2-ylidene)ketones 1a–1c with aroyl 2a–2d and 2-thienyl 2e isothiocyanates for 6–10 h boiling in acetone has been developed. Studies of the antimicrobial and antioxidant activities potential of the obtained compounds revealed that [2-methyl-5-(4-nitrophenyl)-7-thioxo-2,3-dihydro-7H-[1,3]thiazolo[3,2-c]pyrimidine-8-yl](phenyl)methanone 3k, effect on the test culture of M. luteum at a concentration of 0.5% is close to the control drug vancomycin. Moreover, [5-(4-bromophenyl)-2-methyl-7-thioxo-2,3-dihydro-7H-[1,3]thiazolo[3,2-c]pyrimidin-8-yl](phenyl)methanone 3j has an antibacterial effect on the specified test culture at a minimum inhibitory concentration of 15.6 μg/mL. In turn, 1-(2-methyl-5-(thiophen-2-yl)-7-thioxo-2,3-dihydro-7H-[1,3]thiazolo[3,2-c]pyrimidin-8-yl]ethanone 3d can be considered promising for further structural modification to enhance the antioxidant effect. The structure of all synthesized substances was established by spectral analysis (¹H and ¹³C NMR, LC–MS, and FT-IR). Additionally, the structure of compound 3i was confirmed by X-ray diffraction analysis.

Graphical Abstract

KEYWORDS:

• Isothiocyanates
• (1,3-thiazolidin-2-ylidene) ketones
• 7-thioxo[1,3] thiazolo[3,2-c]pyrimidines
• cyclocondensation

Acknowledgment

We are grateful to the National Academy of Science of Ukraine for supporting this study under a Groups of young scientists of the NAS of Ukraine Grant.