3-((3R,4S)-4-{[(S)-1-((S)-3-Benzyloxycarbonyl-2-tert-butoxycarbonylamino-propionyl)-pyrrolidine-2-carbonyl]-amino}-2,2-difluoro-3-hydroxy-5-phenyl-pentanoylamino)-benzoic acid benzyl ester

(R)-2-((3R,4S)-4-{[(S)-1-((S)-2-tert-Butoxycarbonylamino-3-methyl-butyryl)-pyrrolidine-2-carbonyl]-amino}-2,2-difluoro-3-hydroxy-5-phenyl-pentanoylamino)-3-phenyl-propionic acid benzyl ester

(S)-2-((3R,4S)-4-{[(S)-1-((S)-2-tert-Butoxycarbonylamino-3-methyl-butyryl)-pyrrolidine-2-carbonyl]-amino}-2,2-difluoro-3-hydroxy-5-phenyl-pentanoylamino)-3-phenyl-propionic acid benzyl ester

(3R,4S)-4-{[(S)-1-((S)-2-tert-Butoxycarbonylamino-3-methyl-butyryl)-pyrrolidine-2-carbonyl]-amino}-2,2-difluoro-3-hydroxy-5-phenyl-pentanoic acid ethyl ester

{(S)-1-[(S)-2-((1S,2R)-1-Benzyl-3-benzylcarbamoyl-3,3-difluoro-2-hydroxy-propylcarbamoyl)-pyrrolidine-1-carbonyl]-2-methyl-propyl}-carbamic acid tert-butyl ester