Copper(II) triflate promoted multicomponent catalytic clubbing of piperazinyl-thiazoloquinolines and thiazolocoumarins as antimicrobials.

Step economical, multicomponent construction of two series based on quinoline and coumarin ring systems was carried out. Annulation towards the 2-piperazinylthiazole system was established in satisfactory yields, using copper(II) triflate. These multicomponent reaction products were examined for their potential inhibitory effect against two Gram-positive bacteria (Staphylococcus aureus and Bacillus cereus), three Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae) and two fungal species (Aspergillus niger and Candida albicans). In vitro pharmacological screening data demonstrated that the majority of the compounds were found to possess a significant broad-spectrum antimicrobial (25-50 µg/mL of MIC) potential and the results were comparable to control drugs. The structural assignments of final products were done on the basis of IR, 1H NMR, 13C NMR spectroscopy, and elemental analysis. The structure-activity relationship (SAR) was explored to facilitate further development of this class of compounds.