Synthesis of Bis-Dibenzonaphthyridines and Evaluation of their Antibacterial Activity

Reaction of phthalic acid with 2-methyl-4-N-phenylaminoquinoline under PPA condition resulted in the formation of 6-methyldibenzo[b,h][1,6]naphthyridines, whereas the same reaction with 2,4bis(N-phenylamino)quinoline resulted in the dimeric dibenzo[b,h][1,6]naphthyridines. A novel mechanism has been proposed to explain the formation of the unexpected product. Screening for the antibacterial activity against various pathogens, proved that the dimeric analogs showed a better antibacterial activity when compared to their monomeric analogs.