(S)-tert-butyl 2-((R)-3-ethoxy-1-hydroxy-3-oxopropyl)pyrrolidine-1-carboxylate

ethyl (2S,3R,4S)-3-(N-tert-butoxycarbonyl-2'-pyrrolidinyl)-3-hydroxy-2-methylpropanoate

(S)-tert-butyl 2-((1R,2R)-1-hydroxy-2-methyl-3-oxo-3-(phenylthio)propyl)pyrrolidine-1-carboxylate