Green, unexpected synthesis of bis-coumarin derivatives as potent anti-bacterial and anti-inflammatory agents

A green and efficient protocol has been developed and a series of coumarin based pyrano[3,2-c]chromene derivatives (2) have been synthesized using multi-component reaction (MCR) approach. Unexpected 3-coumarinyl-3-pyrazolylpropanoic acids (3) and C-4-C-4 chromenes (5) have been isolated instead of expected product 4 by the reaction of compound (2) in formic acid at 90 degrees C for about 4-5 h and at 130 degrees C for about 8-10 h respectively. Further, C-4-C(4)chromenes (5) formation was confirmed by intramolecular cyclization of compounds (3). These compounds were screened for their biological activities and most of them exhibited promising antibacterial activity. The anti-inflammatory assay was evaluated against HRBC membrane stabilization method and the compounds exhibit excellent anti-inflammatory activity. Molecular docking study has been performed for all the synthesized compounds with Klebsiella pneumoni aeacetolactate synthase and results obtained are quite promising. (C) 2017 Elsevier Masson SAS. All rights reserved.