(2R,3S,RS)-N-(tert-butoxycarbonyl)-3-amino-5-methyl-1-[(4-methylphenyl)sulfinyl]-2-hexanol

(4S,5S)-5-isobutyl-4-hydroxy-2-oxopyrrolidine

(4S,5S)-5-allyl-3-(tert-butoxycarbonyl)-4-iso-butyl-2-oxazolidinone

tert-butyl (S)-2-isobutyl-3,5-dioxopyrrolidine-1-carboxylate

(4S)-4-[(tert-butyloxycarbonyl)amino]-6-methyl-3-oxoheptanoic acid ethyl ester