Novel substituted 1-iminoisoindoline derivatives: Synthesis, structure determination and antiproliferative activity

Novel derivatives of isoindoline, N-phenyl-1-iminophenylisoindoline 6, N-(4-methylphenyl)-1-imino-(4-methylphenyl)-isoindoline 7, N-(pyridin-2-yl)-1-imino-(pyridin-2-yl)-isoindoline 8 and N-(5-methylpyridin-2-yl)-1-imino(5-methylpyridin-2-yl)-isoindoline 9 were prepared by the reaction of condensation of phthalaldehyde and corresponding amines. Structures of all compounds have been studied using one- and two-dimensional 1H and 13C NMR, IR, MS and UV/Vis spectroscopy. The crystal and molecular structures of 7, 8 and 9 were determined by X-ray diffraction on single crystals. In all three molecules the isoindoline system and its N-substituent are approximately coplanar. The crystal structures comprise of discrete molecules linked only by weak C–H⋯N interactions in the case of 8 and 9. NMR analysis showed that conformations of compounds 6 and 7 differ from those of 8 and 9 in solution. Differences between solution and solid state structures were also noticed. All prepared compounds were tested on their antiproliferative activity in vitro. Compound 7 exerted the strongest non-specific antiproliferative effect on all cell lines and compounds 8 and 9 showed selective antiproliferative effect on HepG2 cell line.