Solid-phase synthesis of the cyclic peptide portion of chlorofusin, an inhibitor of p53-MDM2 interactions

The first solid-phase synthesis of the chlorofusin peptide is described. The synthesis involved side-chain immobilization of N(alpha)-Fmoc-Asp-ODmab. Synthesis of the linear peptide, initially incorporating racemic Ade8 and unsubstituted ornithine in place of the chromophore-bearing residue, was followed by cyclization on resin and peptide release to give a mixture of diastereomers. Resynthesis identified (by HPLC) the second isomer as analogous to the natural product. Initial biological assays, using an immunofluorescence method, suggest that the compounds are not cytotoxic but do not inhibit the p53/mdm2 interaction. [structure: see text]