Thiazolyl-pyrazole-biscoumarin synthesis and evaluation of their antibacterial and antioxidant activities

A series of novel 3-(2-oxo-2 H -chromen-3-yl)-1-(4-(2-oxo-2 H -chromen-3-yl)thiazol-2-yl)-5-aryl-1 H -pyrazol-1-ium bromides have been prepared through a one-pot three-component cyclocondensation of various coumarin chalcones, thiosemicarbazide and 2-bromocoumarin. The key features of this reaction are the incorporation of four heterocyclic rings in the structure of target products, using commonly available and inexpensive catalysts, high yields, and simple reaction conditions. Final salt products were obtained by self-capturing of a proton by the nitrogen of the pyrazole moiety. The easy work-up and mild reaction conditions are notable features of this protocol. The antioxidant, antibacterial, and anti-fungal activities of the synthetic products were examined. Most of the compounds showed good biological capacity in comparison to references. Graphical Abstract