Novel Achiral Aryl-Substituted Vanadocenes: Synthesis and Preliminary Cytotoxicity Studies

From the reaction of 6-(4-methoxymethyl-phenyl) fulvene (1a), 6-(N-methyl-pyrrole) fulvene (1b), and 6-(4-dimethylamino- phenyl) fulvene (1c) with LiBEt3H, the corresponding lithium cyclopentadienide intermediates (2a-c) were synthesized. These intermediates were then transmetallated to vanadium with VCl4 to yield the substituted vanadocene dichlorides bis-[(4-methoxymethyl-benzyl) cyclopentadienyl] vanadium(IV) dichloride (3a), bis-[(N-methylpyrrole)2-methylcyclopentadienyl] vanadium(IV) dichloride (3b), and bis-[(p-dimethylaminobenzyl) cyclopentadienyl] vanadium(IV) dichloride (3c). The vanadocene dichloride 3a was characterized by single crystal X-ray diffraction. All three vanadocenes had their cytotoxicity investigated through MTT based preliminary in vitro testing on the human renal cell line Caki-1 in order to determine their IC50 values. Vanadocenes 3a-b were found to have IC50 values of 6.5 and 5.2 mu M, respectively, while 3c displayed a superior value of 1.7 mu M.