Synthesis and Preliminary Cytotoxicity Studies of Achiral Indolyl-Substituted Titanocenes

From the reaction of various 6-indolylfulvenes (1a−f) with Super Hydride (LiBEt3H), followed by transmetalation with titanium tetrachloride (TiCl4), six indolyl-substituted titanocenes, bis[(1-methylindol-2-yl)cyclopentadienyl]titanium(IV) dichloride (3a), bis[(1-methyl-5-methoxyindol-2-yl)cyclopentadienyl]titanium(IV) dichloride (3b), a dihydrochloride derivative of bis[(1-methyl-3-dimethylaminomethylindol-2-yl)cyclopentadienyl]titanium(IV) dichloride (3c), bis[(1-methylindol-3-yl)cyclopentadienyl]titanium(IV) dichloride (3d), bis[(1-methyl-5-methoxyindol-3-yl)cyclopentadienyl]titanium(IV) dichloride (3e), and bis[(1-methylmethoxyindol-3-yl)cyclopentadienyl]titanium(IV) dichloride (3f), were obtained. The six titanocenes 3a−f were tested for their cytotoxicity through MTT-based in vitro tests on CAKI-1 cell lines in order to determine their IC50 values. Titanocenes 3a−f were found to have IC50 values of 47 (±9), 15 (±2), 8.2 (±1.9), 21 (±5), 11 (±1), and 170 (±40) μM, respectively.