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

[(S)-1-((S)-1-{(S)-[(1R,2R)-2-((S)-1-Butylcarbamoyl-ethylcarbamoyl)-cyclopentyl]-hydroxy-methyl}-3-methyl-butylcarbamoyl)-3-methylsulfanyl-propyl]-carbamic 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-4-methylsulfanyl-butyrylamino)-1-hydroxy-4-methyl-pentyl]-4-oxo-cyclopentanecarbonyl}-amino)-propionic acid 2,2,2-trichloro-ethyl ester

(S)-2-({(1R,2R)-2-[(1S,2S)-2-((S)-2-tert-Butoxycarbonylamino-4-methylsulfanyl-butyrylamino)-1-hydroxy-4-methyl-pentyl]-cyclopentanecarbonyl}-amino)-3-methyl-butyric acid benzyl ester