{(R)-1-[(R)-1-{(S)-1-[(R)-2-(tert-Butyl-dimethyl-silanyloxy)-1-(3-hydroxy-phenyl)-ethylcarbamoyl]-ethylcarbamoyl}-2-(4-fluoro-3-nitro-phenyl)-ethylcarbamoyl]-3-methyl-butyl}-methyl-carbamic acid tert-butyl ester

{(S)-1-[(R)-1-(3-Allyloxy-phenyl)-2-(tert-butyl-dimethyl-silanyloxy)-ethylcarbamoyl]-ethyl}-carbamic acid allyl ester

(S)-2-Amino-N-{(R)-2-(tert-butyl-dimethyl-silanyloxy)-1-[3-(tert-butyl-dimethyl-silanyloxy)-phenyl]-ethyl}-2-(3-isopropoxy-phenyl)-acetamide

[(S)-[(R)-2-(tert-Butyl-dimethyl-silanyloxy)-1-(3-hydroxy-phenyl)-ethylcarbamoyl]-(3-isopropoxy-phenyl)-methyl]-carbamic acid tert-butyl ester

[(S)-[(R)-1-(3-Allyloxy-phenyl)-2-(tert-butyl-dimethyl-silanyloxy)-ethylcarbamoyl]-(3-isopropoxy-phenyl)-methyl]-carbamic acid tert-butyl ester