A straightforward procedure for the synthesis of enantiopure polysubstituted piperidines is reported. It involves the direct generation of chiral non-racemic oxazolo[3,2-a]piperidone lactams that already incorporate carbon substituents on the heterocyclic ring and the subsequent removal of the chiralauxiliary. The key step is a cyclocondensation reaction of (R)-phenylglycinol or other amino alcohols
[GRAPHICS]Starting from a common chiral bicyclic lactam 11, enantiopure trans- or cis-3-ethyl-4-piperidineacetate derivatives are obtained by conjugate addition of an enolate or a cuprate to the unsaturated lactams 12 or 18, respectively.