Synthesis and preliminary cytotoxicity studies of achiral pyrrolyl-substituted titanocenes

Abstract

From the reaction of various 6-pyrrolylfulvenes ( 3a– 3d) with Super Hydride (LiBEt 3H), lithiated cyclopentadienide intermediates ( 4a– 4d) were synthesised. These intermediates were then transmetallated with titanium tetrachloride TiCl 4 to yield the pyrrolyl-substituted titanocenes bis-[((1-(4-methoxybenzyl)-pyrrole)2-)cyclopentadienyl]titanium(IV) dichloride ( 5a), bis-[((1-(4-methoxyphenyl)-pyrrole)2-)cyclopentadienyl]titanium(IV) dichloride ( 5b), bis-[((2,4-bis(4-methoxyphenyl)-1-methyl-pyrrole)2-)cyclopentadienyl]titanium(IV) dichloride ( 5c), bis-[((2-(4-methoxyphenyl)-1-methyl-pyrrole)2-)cyclopentadienyl]titanium(IV) dichloride ( 5d). Titanocene 5b crystallised and was characterised by X-ray crystallography. The four titanocenes 5a– 5d were tested for their cytotoxicity through MTT-based in vitro tests on CAKI-1 cell lines in order to determine their IC 50 values. Titanocenes 5a– 5d were found to have IC 50 values of 440 (±35), 68 (±14), 105 (±30), and 36 (±7) μM.