(S)-N-[Bis-(4-methoxy-phenyl)-methyl]-2-[(2R,3R)-2-tert-butoxycarbonylamino-3-(tert-butyl-dimethyl-silanyloxy)-3-(3-chloro-4-hydroxy-phenyl)-propionylamino]-succinamic acid

(R)-((S)-2-Amino-3-{[bis-(4-methoxy-phenyl)-methyl]-carbamoyl}-propionylamino)-(3,5-dihydroxy-4-methoxy-phenyl)-acetic acid tert-butyl ester

(S)-2-Amino-N-[bis-(4-methoxy-phenyl)-methyl]-succinamic acid 2-trimethylsilanyl-ethyl ester

(S)-2-[(2R,3R)-2-Amino-3-(4-fluoro-3-nitro-phenyl)-3-hydroxy-propionylamino]-N-[bis-(4-methoxy-phenyl)-methyl]-succinamic acid 2-trimethylsilanyl-ethyl ester