A Convenient Synthesis of Bipyrido-Fused Coumarins and Their Biological Evaluation

A convenient and efficient strategy has been devised for the synthesis of bipyrido-fused coumarins employing Kröhnke's pyridine synthesis approach. In the present work, 4-hydroxycoumarins 1a–d were reacted with appropriate chalcones 2a–c to afford desired bipyridyl-fused coumarins 3a–l. The structures of all the newly synthesized compounds 3a–l were ascertained by IR, ¹H NMR, ¹³C NMR, mass spectral data, and elemental analyses. The compounds were further evaluated for their antimicrobial response against representative panel of pathogens, and the results thus obtained were compared with those of standard drugs. Few of the derivatives 3c, 3f, and 3i exhibited promising potency.