diphenyl 1-(benzyloxycarbonylamino)-2-{4-[N,N'-bis(tert-butyloxycarbonyl)guanidino]phenyl}ethanephosphonate

benzyl 1-(bis(4-acetamidophenoxy)phosphoryl)-2-(4-amino-phenyl)ethylcarbamate

di-(4-acetamidophenyl) 1-[(N-benzyloxycarbonyl-O-tert-butyl-D-seryl)-L-alanyl]amino-2-{4-[N,N'-bis(tert-butyloxycarbonyl)guanidino]phenyl}ethanephosphonate

diphenyl 1-[(N-o,o-dimethylbenzoyl-O-tert-butyl-D-seryl)-L-alanyl]amino-2-[4-(N,N'-bis(tert-butyloxycarbonyl)guanidino)phenyl]ethanephosphonate