(R)-N1-[(2R,3S)-3-((2S,3R)-2-Amino-3-hydroxy-butyrylamino)-2-hydroxy-4-phenyl-butyl]-2-tert-butyl-N4-(1-ethyl-propyl)-succinamide

4-[(1-Ethylpropyl)amino]-2(R)-tert-butyl-4-oxobutanoic acid

(S)-3-tert-Butylcarbamoyl-4,4-dimethyl-pentanoic acid benzyl ester

[(S)-1-((1S,2R)-1-Benzyl-3-{(R)-2-[(1-ethyl-propylcarbamoyl)-methyl]-3,3-dimethyl-butyrylamino}-2-hydroxy-propylcarbamoyl)-2-carbamoyl-ethyl]-carbamic acid benzyl ester

[(1S,2R)-1-Benzyl-3-((S)-3-tert-butylcarbamoyl-4,4-dimethyl-pentanoylamino)-2-hydroxy-propyl]-carbamic acid tert-butyl ester