The preparation of a series of N-hydroxy peptides is described, along with their acylation on the oxygen of the pseudopeptide bond. Nineteen N-acyloxy peptides, first examples of this new class of pseudopeptides, were thus synthesized; they present a range of acyl groups, including N-protected amino acyl groups. Possibilities of elongation for these pseudopeptides were also investigated.
The preparation of cyclic hexapeptides from N-hydroxy tripeptides building blocks is described. Introduction of an unsaturated chain on the hydroxamate oxygen followed by fragment coupling leads to N,N'-dialkenoxy hexapeptides that are efficiently cyclized through a ring-closing metathesis reaction. The length of the alkene chains allows the modulation of the ring size: the synthesis of 17- and 18-membered