(S)-2-[((1R,2R)-2-{(1S,2S)-2-[(S)-2-((S)-2-Acetylamino-4-methyl-pentanoylamino)-4-methylsulfanyl-butyrylamino]-1-hydroxy-4-methyl-pentyl}-cyclopentanecarbonyl)-amino]-3-methyl-butyric acid

[(S)-1-((S)-1-{(S)-[(1R,2R)-2-((S)-1-Butylcarbamoyl-2-methyl-propylcarbamoyl)-4-oxo-cyclopentyl]-hydroxy-methyl}-3-methyl-butylcarbamoyl)-3-methylsulfanyl-propyl]-carbamic acid tert-butyl ester

(4S)-isobutyl-(5S)-((2R)-methoxycarbonyl-4-oxo-cyclopentyl)-2,2-dimethyl-oxazolidine-3-carboxylic acid tert-butyl ester

(S)-2-({(1R,2R)-2-[(1S,2S)-2-((S)-2-tert-Butoxycarbonylamino-4-methylsulfanyl-butyrylamino)-1-hydroxy-4-methyl-pentyl]-cyclopentanecarbonyl}-amino)-propionic acid 2,2,2-trichloro-ethyl ester

(S)-2-[((1R,2R)-2-{(1S,2S)-2-[(S)-2-tert-Butoxycarbonylamino-3-(trityl-carbamoyl)-propionylamino]-1-hydroxy-4-methyl-pentyl}-cyclopentanecarbonyl)-amino]-propionic acid benzyl ester