(5S)-4-hydroxy-5-isobutyl-1-t-butoxycarbonylpyrrol-2(5H)-one

(2'S)-5-[(1-hydroxy-4-methyl-2-t-butoxycarbonylamino)-pentylidene]-2,2-dimethyl-1,3-dioxane-4,6-dione

(4S,5S)-3-(tert-butoxycarbonyl)-5-cyanomethyl-4-isobutyl-2,2-dimethyl-1,3-oxazolidine

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

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