Synthesis of Some 2-(3-Alkyl/aryl-5-trifluoromethylpyrazol-1-yl)-4-(coumarin-3-yl)thiazoles as Novel Antibacterial Agents

Abstract

Herein, we describe a one-pot synthesis of some novel 2-(3-alkyl/aryl-5-trifluoromethylpyrazol-1-yl)-4-(coumarin-3-yl)thiazoles (6) involving the reaction of 3-alkyl/aryl-5-hydroxy-5-trifluoromethyl-4,5-dihydropyrazole-1-thiocarboxamides (3) with 3-bromoacetylcoumarins (5) in the presence of sodium carbonate in ethanol. Reaction of 3 with 5 in the absence of sodium carbonate, however, resulted in the formation of 2-(3-alkyl/aryl-5-hydroxy-5-trifluoromethyl-4,5-dihydropyrazol-1-yl)-4-(coumarin-3-yl)thiazoles, which were subsequently dehydrated to 6 by refluxing in ethanol in the presence of sodium carbonate. The structure of the synthesized compounds (6) was confirmed by infrared (IR), mass, ¹H NMR, and ¹³C NMR spectra and elemental analysis data. Newly synthesized compounds (6) showed moderate to good activity against Gram-positive bacteria.

GRAPHICAL ABSTRACT

Keywords:

• 2-(3-Alkyl/aryl-5-trifluoromethylpyrazol-1-yl)-4-(coumarin-3-yl)thiazoles
• 3-alkyl/aryl-5-hydroxy-5-trifluoromethyl-4
• antibacterial
• 3-(2-bromoacetyl)coumarins
• 5-dihydropyrazole-1-thiocarboxamides
• sodium carbonate

ACKNOWLEDGMENTS

Thanks are due to Sophisticated Analytical Instrument Facility (SAIF), Central Drug Research Institute (CDRI), Lucknow; SAIF, Panjab University, Chandigarh, India; and University of California San Francisco (UCSF), USA, for providing ¹⁹F NMR, elemental analyses, and HRMS spectra, respectively.

SUPPLEMENTAL MATERIAL

Supplemental data for this article can be accessed on the publisher’s website.