Synthesis and biological evaluation of 4,4-dimethyl-5,5-di(1-methylethyl)-2,3,4,5-tetrahydro-1 H-dipyrrolo[3,4-d:2,1-f][1,2]azasiline-1,3-dione and other pyrrolediones as new antibacterial active agents.

The UV-light induced photosubstitution of 3,4-dibromo-2,5-dihydro-1H-2,5-pyrroledione (2) [1] with pyrrole derivatives leads to 3-mono- and 3,4-disubstituted pyrrolediones depending on the starting material. These pyrrole homologues of arcyriarubin A (1) are further processed by nucleophilic substitution of the remaining bromine substitutent with pyrrolidine. Cleavage of the protecting group affords the free pyrrole substituents. By UV-light irradiation the azasiline-system (6) is accessible, and its structure was established by X-ray methods. The in vitro antibacterial activity of the pyrrolediones was evaluated, and a strong activity of the compounds 4, 7, 8 and 12 against the methicillin- and ciprofloxacin-resistant bacterium Staphylococcus aureus 134/94 was established.