In this paper, we report the synthesis of peptidomimetics containing oxazolidin-2-one and oxazolidine rings. The two of these heterocyclic peptidomimetics novel series were obtained from serine as starting material through an efficient intramolecular cyclization. In the case of oxazolidine, the formation of only one diastereoisomer was observed.

An improved synthesis of unsaturated γ-lactams by condensation of various primary amines with 2,5-dimethoxy-2,5-dihydrofuran is described. A modified mechanism for this reaction is suggested. Synthesis of their N-α-methoxylated derivatives, as N-acyliminium ion precursors, is also reported. Finally, a short synthesis of (±)-crispine A is presented as an illustrative application.