Synthesis and antitumor activity of (diamine)platinum(II) complexes of benzylmalonate derivatives

(Diamine)platinum(II) complexes of benzylmalonate derivatives as a leaving group designed in a wide range of lipophilicity and water-solubility were prepared and their antitumor activities were attempted to correlate to their lipophilicity or solubility. A good relationship was observed between their in vitro toxicity and solubility of the title complexes with the same carrier ligand, DACH (trans-(±)-1,2-diaminocyclohexane): The most soluble complexes are most cytotoxic whereas the least soluble complexes are least cytotoxic. However, no relationship could be established between their in vivo activity and their lipophilicity or solubility presumably due to other pharmacokinetic factors involved in vivo. The molecular structure of (IPA)₂Pt(DBM)·2CH₃OH (IPA = isopropylamine; DBM = dibenzylmalonate) was determined by X-ray diffraction: space group P2₁/n, a = 11.433 (3), b = 14.461 (4), c = 17.478 (4) Å, β = 97.25 (3)°, z = 4, R = 0.0437.