Synthesis and bio-evaluation of novel 7-hydroxy coumarin derivatives via Knoevenagel reaction

Coumarin and 7-hydroxy coumarins have great significance as natural fragrances, having a characteristic odour like vanilla beans and their hydroxy position at 7 has importance in biosynthesis. Treatment of 8-formyl-7-hydroxy coumarin with N,N-disubstituted cyano acetamides in the presence of piperidine afforded novel 8-substituted-7-hydroxy coumarin derivatives. Their structures were characterized by IR, H-1, C-13 NMR, mass spectral and elemental analysis data. Two out of these 12 compounds, i.e. 2-Cyano-3-(7-hydroxy-2-oxo-2H-chromen-8-yl)-N-[2-(2-methoxy-phenoxy)-ethyl]-acrylamide and 2-Cyano-N-(2,5-dihydro-thiazol-2-yl)-3-(7-hydroxy-2-oxo-2H-chromen-8-yl)-acryl amide showed enhanced in vitro antifungal activity against Candida albicans and Aspergillus niger vis-A -vis standard, i.e. fluconazole, and enhanced in vitro antibacterial activity against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa vis-A -vis standard, i.e. norfloxacin. .