Microwave-assisted synthesis of novel 4H-chromene derivatives bearing 2-aryloxyquinoline and their antimicrobial activity assessment

A new series of 4H-chromene derivatives 6a–x bearing 2-aryloxyquinoline nucleus have been synthesized under microwave irradiation by reaction of 2-aryloxyquinoline-3-carbaldehyde 3a–l, malononitrile 4, and compounds (Cyclohexanedione, Dimidone) 5a–b in the presence of NaOH as the basic catalyst. All the compounds were screened against three Gram-positive bacteria (Streptococcus pneumoniae, Clostridium tetani, Bacillus subtilis), three Gram-negative bacteria (Salmonella typhi, Vibrio cholerae, Escherichia coli) and two fungi (Aspergillus fumigatus, Candida albicans) using the broth microdilution MIC (Minimum Inhibitory Concentration) method. Upon study of the antimicrobial screening, it has been observed that a majority of the compounds were found to be active against C. tetani and B. subtilis as well as against C. albicans as compared to the standard drugs.