One-pot, three-component synthesis and in vitro anti-bacterial evaluation of some novel chromeno[4,3-d]pyrimidine, thiazol-2H-chromens, and thiadiazol-2H-chromen derivatives

Three series of 3-amino/amido-alkyl-4-hydroxycoumarin derivatives have been efficiently synthesized by threecomponent reaction of 4-hydroxycoumarin with aromatic aldehydes and urea/2-aminothiazole/2-amino-4methylthiadiazole in the presence of [Caffeine-H][ClCH2COO] IL as a green catalyst under solvent-free conditions. The chemical structures of all the compounds were confirmed by spectroscopic methods as well as elemental analysis. This environmentally friendly, solvent-free, and efficient strategy for the assembly of various 3-amino/amido-alkyl-4-hydroxycoumarin derivatives, including chromeno[4,3-d]pyrimidines (6), thiazol-2Hchromens (7), and thiadiazol-2H-chromen (8) has been developed. In addition, the anti-bacterial activities of target compounds against Gram-negative and Gram-positive bacteria in vitro were determined. Among these compounds 6b, 6e, 6c, 8c and 8d exhibited antibacterial effects. According to the results, it seems that the antibacterial effect of the ligands is more on Gram-positive bacteria.