Highly efficient synthesis of (R)- and (S)-piperazic acids using proline-catalyzed asymmetric α-hydrazination

The highly efficient synthesis of (R)- and (S)-piperazic acids, components of naturally occurring antibiotic cyclodepsipeptides, was achieved in 80% overall yield by the use of a proline-catalyzed asymmetric α-hydrazination as the key step.