A Water-Soluble Polyamide Containing cis-dicarboxylato-chelated Platinum(II)

For use as a macromolecular drug carrier in the development of carrier-bound platinum anticancer drugs, the water-soluble polyamides 1 and 2 have been synthesized, meeting the specific structural requirement of the presence of pairs of carboxyl groups directly attached to the polymer main chain in 1,1geometry. The synthesis involves solution polymerization of diamines with the key monomer, 2,2-bis(2-methoxycarbonylethyl)malonic acid (6), prepared from diethyl malonate via several intermediary malonic acid derivatives. The diamine monomers are 1,3-diaminopropane and 4,7,10-trioxa-1,13-tridecanediamine, leading, respectively, to the polyamides 1 and 2. The polymerization proceeds in the presence of anhydrous sodium carbonate. Rigorous purification by precipitation, reprecipitation, and aqueous dialysis, followed by freeze-drying, furnishes the target compounds as water-soluble, solid polymers, which are structurally characterized by spectroscopic and microanalytical techniques. The exemplifying platination of carrier 2 with DACH-Pt (trans-1,2-diaminocyclohexanediaquaplatinum(II) dinitrate) provides the conjugate 2-Pt as a water-soluble compound with a Pt content of 8%.