{(1S)-1-[(4R)-4-(3-azido-propyl)-5-oxo-tetrahydro-furan-(2S)-2-yl]-2-phenyl-ethyl} carbamic acid tert-butyl ester

[(1S)-1-{(1S)-1-[(4R)-4-(3-azido-propyl)-5-oxo-tetrahydro-furan-(2S)-2-yl]-2-phenyl-ethylcarbamoyl}-2-(trityl-carbamoyl)-ethyl]-carbamic acid benzyl ester

(2R,4S,5S)-5-((S)-2-(((benzyloxy)carbonyl)amino)-4-oxo-4-(tritylamino)butanamido)-4-((tert-butyldimethylsilyl)oxy)-6-phenyl-2-(3-((triphenylphosphonio)amino)propyl)hexanoate

(2R)-2-(3-azido-propyl)-(5S)-5-[(2S)-2-benzyloxycarbonylamino-3-(trityl-carbamoyl)-propionylamino]-(4S)-4-(tert-butyl-dimethyl-silanyloxy)-6-phenyl-hexanoic acid

(5S)-5-[(2S)-2-benzyloxycarbonylamino-3-(trityl-carbamoyl)-propionylamino]-(4S)-4-(tert-butyl-dimethyl-silanyloxy)-(2R)-2-(3-N,N'-bis-t-boc-guanidino-propyl)-6-phenyl-hexanoic acid