Crystallization-Induced Chiral Inversion As the Key Step for Synthesis of (S)-2-Acetylthio-3-phenylpropanoic Acid from l -Phenylalanine

[reaction: see text] A novel crystallization-induced chiral inversion of (S)-2-bromo-3-phenylpropanoic acid to its (R)-enantiomer with excellent enantiomeric excess (96-99%) is achieved. Optically pure (S)-2-acetylthio-3-phenylpropanoic acid can be prepared in good yield from inexpensive and commercially available l-phenylalanine via diazotization/bromination, chiral inversion, and thioacetate substitution reactions.