Hexachloroplatinic acid (I) was reduced to potassium tetrachloroplatinate (II) using hydrazine. Treatment of (II) with KI produced the tetraiodoplatinate (III), which was converted to the diamino compound (IV) by reaction with isopropylamine. Conversion to the dinitrate (V) was then effected by iodide ion exchange with silver nitrate. Diels-Alder condensation of maleic anhydride (VI) with furan (VII) furnished adduct (VIII), which was further hydrogenated to (IX) using Pd/C. Then, basic hydrolysis of the cyclic anhydride in the presence of the platinum complex (V) afforded the title compound.
The Diels-Alder cycloaddition between maleic anhydride (I) and furan (II) produced adduct (III). Subsequent double-bond hydrogenation in the presence of Pd/C furnished the saturated anhydride (IV).
The platinum nitrate derivative (X) was prepared by two related procedures. Halogen-exchange of potassium tetrachloroplatinate (V) with KI produced the tetraiodoplatinate (VI), which was subsequently reacted with trans-1,2-diaminocyclohexane (VII) to give the diamino chelate (VIII). Alternatively, diamine (VII) was reacted with tetrachloroplatinate (V), yielding chelate (IX). Treatment of either iodo compound (VIII) or its analogous chloride (IX) with silver nitrate furnished the dinitrate compound (X). Finally, the diacid formed by basic hydrolysis of anhydride (IV) was in situ complexed with the platinum compound (X) to generate the title platinum complex.