We describe a straightforward synthesis of 9-substituted 3-aminooxazolidinopiperidin-2-ones 4. Somederivatives were prepared for use in peptide synthesis as rigidified surrogates of the Ala-Prodipeptide. Analysis of the amide derivatives 14 by NMR experiments and molecular mechanics/dynamics calculations shows that the major isomer 14a has a stronger propensity than the minorisomer 14b to adopt β-turn conformations, and the calculations indicate that in water 14a adoptsa stable βII‘ turn conformation.