Stereocontrolled syntheses for the six diastereomeric 1,2-dihydroxy-4,5-diaminocyclohexanes: PtII complexes and P-388 antitumor properties.

Stereocontrolled syntheses for the six diastereomeric 1,2-dihydroxy-4,5-diaminocyclohexanes 3a-f from cyclohexene diamines cis-4 and trans-5 are described. Cbz-protected species cis-9 and trans-11, respectively, served as a source of stable Cbz-protected precursors to these cyclohexanediol diamines (CDD), which were liberated upon catalytic (H2, Pd/C) hydrogenation. Catalytic osmylation of 9 afforded a mixture of diastereomeric diols 13 and 14, which served as precursors to cis-anti-cis CDD 3b and cis-syn-cis CDD 3a, respectively, whereas osmylation of 11 yielded the expected single product 12, the precursor to cis-anti-trans CDD 3d. Epoxidation of olefins 9 and 11 afforded oxiranes 15 and 17, respectively, which upon acid-catalyzed hydrolysis produced the corresponding Cbz-protected diols 16 and 18, which served as precursors to CDD trans-anti-cis 3c, and trans-anti-trans 3e. Formation of diol 18 from oxirane 17 was accompanied by formation of 2-oxa-4-azabicyclo[3.3.1]nonan-3-one 19. CDD trans-syn-trans 3f was prepared from diol 12 via regioselective monoacetylation, yielding 22, followed by oxidation to afford ketone 24. Sodium borohydride reduction and acetylation produced diacetate precursor 26. PtIICl2 complexes of five of the diamines (3a-d,f) are described, and their activities were compared with cisplatin (1) by employing P-388 leukemia implanted CDF1 mice. The data indicate that stereochemistry of the amino groups on the cyclohexanediamine ligand modulate the expression of toxic effects, and depending upon hydroxyl and amino group stereochemistry, there is a marked effect on complex formation (e.g., Cl2PtII-3e) and solubility characteristics (e.g., Cl2PtII-3c). Acetylation of the hydroxyl functions in selected isomers (28a-c) rendered the PtII complexes inactive. A single-crystal X-ray structure of compound 3a was determined at room temperature and indicated the cis-syn-cis arrangement of the OH and NH2 groups.