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

Abstract

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.

Facile access to 2‐amino‐4‐aryl‐5H‐chromeno[4,3‐b]pyridine‐3‐carbonitriles through a strategy of one‐pot Michael/cyclization reaction

“…However, except for ammonium acetate, no reaction products were produced when other bases were used. Consequently, ammonium acetate was uniquely chosen for the one-pot reaction with the generation of compound 4a in 80% isolated yield (Table 1, entries [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15].…”

“…Most recently, chromeno [4,3-b]pyridine has been identified as the central framework in various natural products [1][2][3][4][5]. Many diverse chromeno [4,3-b]pyridine derivatives and more structures featured with chromeno [4,3-b]pyridine fragment have multifarious biological activities (Figure 1), such as topoisomerase inhibitor [6,7], anticancer agent [8,9], antimicrobial activity [10], α-glucosidase inhibitory activity [11], ecto-5 0 -nucleotidase inhibitory activity [12], antioxidative activity [13]. In addition, some of these compounds can be used as fluorescent dye [14], as well as fluorescent probe for monitoring sulfur dioxide derivatives [15,16], lipid droplets [17].…”

An Overview on the Synthesis of Fused Pyridocoumarins with Biological Interest

“…In 2019, Giri and Brahmbhadtt synthesized bipyridyl-fused coumarins 209a – l by the Krohnke’ reaction of 4-hydroxycoumarins 120 with chalcones 208a – c and ammonium acetate in glacial acetic acid [ 154 ]. In the proposed plausible mechanism, the intermediate B was formed by the Michael reaction of carbanion A to the chalcone 208a .…”