Asymmetric Synthesis. 32. A New Access to Enantiomerically Pure (S)-(-)-Pipecolic Acid and 2- or 6-Alkylated Derivatives
摘要:
Enantiomerically pure (S)-(-)-pipecolic acid (5) was synthesized in four steps and 47% overall yield starting from 2-cyano-6-phenyloxazolopiperidine (1). A general strategy is described for preparing 2-alkylated and 6-alkylated pipecolic acid 7a-c and 11a-c using diastereoselective procedures.