{3-[(S)-4-((S)-1-Methylcarbamoyl-2-naphthalen-2-yl-ethyl)-1-(2-nitro-benzenesulfonyl)-3-oxo-piperazin-2-yl]-propyl}-carbamic acid benzyl ester

{3-[(S)-1-[(R)-2-tert-Butoxycarbonylamino-3-(4-fluoro-phenyl)-propionyl]-4-((S)-1-methylcarbamoyl-2-naphthalen-2-yl-ethyl)-3-oxo-piperazin-2-yl]-propyl}-carbamic acid benzyl ester

(S)-2-[(R)-2-[(S)-2-(3-Benzyloxycarbonylamino-propyl)-4-((S)-1-methylcarbamoyl-2-naphthalen-2-yl-ethyl)-3-oxo-piperazin-1-yl]-1-(4-fluoro-benzyl)-2-oxo-ethylcarbamoyl]-piperidine-1-carboxylic acid tert-butyl ester