It was shown previously that a number of compounds containing various aromatic and heterocyclic systems in position 3 of the coumarin ring have antibacterial activity [1 -31. Continuing the work on the synthesis, and study of the properties and biological activity ofphosphonium and ammo- nium derivatives of coumarin [4], we synthesized phospho- rus- and nitrogen-containing systems of coumarins, 5,6-ben- zocoumarins and studied their antimicrobial activity. ...