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

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

{3-[(S)-1-[(R)-2-((S)-2-Acetylamino-4-carbamoyl-butyrylamino)-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)-5-Benzyloxycarbonylamino-2-(2-nitro-benzenesulfonylamino)-pentanoic acid

{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