[(S)-2-Methyl-1-((R)-5-oxo-tetrahydro-furan-2-yl)-propyl]-carbamic acid tert-butyl ester

(4R,5S)-5-tert-Butoxycarbonylamino-4-hydroxy-6-methyl-heptanoic acid ethyl ester

(4S,5S)-5-tert-Butoxycarbonylamino-4-hydroxy-6-methyl-heptanoic acid ethyl ester

(4S,5S)-5-(2-Ethoxycarbonyl-ethyl)-4-isopropyl-2-oxo-oxazolidine-3-carboxylic acid tert-butyl ester

(4R,5S)-5-tert-Butoxycarbonylamino-4-methanesulfonyloxy-6-methyl-heptanoic acid ethyl ester