AbstractDibenzobarrelene (I) was used as a starting compound for the synthesis of some new 3a,4,9,9a-tetrahydro-4,9-[1,2]benzeno-1H-benzo[f]isoindole-1,3(2H)-diones, N-substituted with: 4-toluenesulfonyloxy, III; butoxy, IV; 3-bromopropoxy, V; 3-(4-phenylpiperazin-1-yl)propoxy, VI; 3-chloro-3-oxopropyl, VIII; 3-(4-phenylpiperazin-1-yl)-3-oxopropyl, IXa; 3-(4-methylpiperazin-1-yl)-3-oxopropyl, IXb; 3-oxo-3-(piperidin-1-yl)propyl, X; 3-morpholino-3-oxopropyl, XI; 3-phenylamino-3-oxopropyl, XII; 2-acetylaminoethyl, XIV; 2-aminoethyl, XV, and 2-acetoxyethyl, XVI. Newly synthesized compounds were characterized by IR, 1H and 13C NMR, and mass spectral data. Selected products were tested for antimicrobial activity.