diphenyl 1-amino-2-(4-(N,N'-bis(tert-butyloxycarbonyl)guanidino)phenyl)ethyl-phosphonate

2-(3-tert-butoxy-2-phenylmethanesulfonylamino-propionylamino)-propionic acid

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

4-(tert-butyloxycarbonylamino)phenylacetaldehyde