3-<<(1,1-dimethylethoxy)carbonyl>amino>-12-oxo-2,4,11-triaza-tetradec-2-enedioic acid, 1-<1,1-dimethyl ester>

ethyl 6-((tert-butoxycarbonyl)amino)-2,2-dimethyl-4,15-dioxo-3-oxa-5,7,14-triazahexadec-5-en-16-oate

4-[N',N''-bis(tert-butyloxycarbonyl)guanidino]phenyl N-(benzyloxycarbonyl)-α-methyl-D-phenylalaninate

4-[N',N''-bis(tert-butyloxycarbonyl)guanidino]phenyl N-(benzyloxycarbonyl)-α-methyl-L-phenylalaninate

N-(N-(3-tetrahydropyranyl)-O-t-butyl-(S)-α-aspartyl)-2(S)-{2-[N-(N,N'-di-t-butoxycarbonylamidino)-4-piperidyloxy]ethyl}piperidine