Reaction and antibacterial efficacy of active methylene compounds with coumarin derivatives

New coumarin derivatives namely (5-oxo-chromeno[3,2-c] dihydropyran derivatives 2a, b, 3a, b), (3-acetyl-4-aryl-2-methyl-5-oxo-chromeno[3,2-c]2,3,4- trihydropyran 4a, b), (2-amino-5-oxo-4H, 5H-pyrano[3,2-c]chromene-3-carbonitriIe 5a, b and 2-amino-5-oxo-3,4,4a, 10b-tetrahydro-2H, 5H-pyrano[3,2-c]chromene-3- carboxylic acid amide 6a, b) were synthesized starting from 3-arylidene chromen-2,4-dione derivatives. The structures of the obtained compounds were confirmed by analytical elemental analysis, IR, 1H-NMR and mass spectra. The new compounds were screened for their antibacterial activity, Compound 3a was the most active compound against gram positive and gram negative bacteria.