Solution/solid-phase synthesis of partially modified retro-ψ[NHCH(CF3)]-peptidyl hydroxamates

The synthesis of a novel family of partially-modified (PM) retropeptidyl hydroxamates incorporating a [CH(CF3)CH2CO] unit as a surrogate of the conventional malonyl group, has been accomplished both in solution and in solid-phase. The key step is the Michael-type N-addition of free or polymer bound α-amino hydroxamates to 3-(E-enoyl)-1,3-oxazolidin-2-ones, which takes place very effectively, although with low stereocontrol. A number of tri- and tetra-peptidyl hydroxamates were obtained either in diastereomerically pure form (by solution-phase synthesis, after chromatographic purification), or as mixtures of two epimers in very good chemical purity (by solid-phase, after release from the resin), demonstrating that this method is suitable for preparing combinatorial libraries of PM retro-ψ[NHCH(CF3)]-peptidyl hydroxamates for screening as metalloprotease inhibitors.