Synthesis of chiral piperazin-2-ones as model peptidomimetics

The enantiospecific synthesis of (3S,6R)-6-ethoxycarbonyl-3-(p-hydroxybenzyl)piperazin-2-one (1) and (3S)-1-(ethoxycarbonylmethyl)-3-(p-hydroxybenzyl)piperazin-2-one (2) and their enantiomers is described. The chiral C-6 centre of (1) is generated by a regiospecific protonation of the enamide precursor.