New biscoumarin and dihydropyran derivatives as antimicrobials

In an attempt to find a new class of antimicrobial agents, a series of biscoumarin (1-4) and dihydropyran (5 and 6) derivatives were prepared. These compounds were screened for their in vitro antibacterial activity against Staphylococcus aureus (S. aureus ATCC 29213), methicillin-resistant S. aureus (MRSA XJ 75302), vancomycin-intermediate S. aureus (Mu50 ATCC 700699), and USA 300 (Los Angeles County clone, LAC). There are two classical intramolecular O-H center dot center dot center dot O hydrogen bonds (HBs) in the structures of biscoumarins 1-4 and the corresponding total HB energy were further performed with the density functional theory (DFT) [B3LYP/6-31G*] method.