(2S)-2-[[(2R,3R)-3-phenyl-2-(sulfanylmethyl)butanoyl]amino]propanoic acid
(2S)-2-[[(2R,3R)-2-(mercaptomethyl)-1-oxo-3-phenylbutyl]amino]propanoic acid
(2S)-2-[[(2R,3R)-2-(mercaptomethyl)-3-phenyl-butanoyl]amino]propionic acid