[((S)-2-tert-Butoxycarbonylamino-4-phenyl-butyryl)-(3-phenyl-propyl)-amino]-acetic acid methyl ester

(S)-3-Butyl-1-(3-phenyl-propyl)-piperazine-2,5-dione

[(S)-3,6-Dioxo-2-phenethyl-4-(3-phenyl-propyl)-piperazin-1-yl]-acetic acid

2-[(S)-2-Benzhydryl-3,6-dioxo-4-(3-phenyl-propyl)-piperazin-1-yl]-N-((S)-1-{(S)-1-[imino-(2,2,5,7,8-pentamethyl-chroman-6-sulfonylamino)-methyl]-piperidin-3-ylmethyl}-2-oxo-2-thiazol-2-yl-ethyl)-acetamide

[((S)-2-Amino-3-phenyl-propionyl)-(3-phenyl-propyl)-amino]-acetic acid methyl ester