(3R,4S,5R)-3,4-Dihydroxy-5-hydroxymethyl-pyrrolidin-2-one

(3R,4R,5R)-3,4-epoxy-5-[(1-ethoxy)ethoxymethyl]pyrrolidin-2-one

(R)-[(4R,5S)-4-(1-Ethoxy-ethoxymethyl)-2-oxo-oxazolidin-5-yl]-hydroxy-acetic acid methyl ester

(2R,3R,4R)-N-benzyl-4-(N-tert-butoxycarbonyl)amino-2,3-epoxy-5-[(1-ethoxy)ethoxy]pentanamide

(2R,3R,4R)-N-benzyloxy-4-(N-tert-butoxycarbonyl)amino-2,3-epoxy-5-[(1-ethoxy)ethoxy]pentanamide