Ethyl (S)-1-((1-((4-((((4-nitrophenoxy)carbonyl)oxy)methyl)phenyl)amino)-1-oxo-5-ureidopentan-2-yl)carbamoyl)cyclobutane-1-carboxylate
(S)-N-(5-(2,5-Dioxo-2,5-dihydro-1H-pyrrol-1-yl)pentyl)-N-(1-((4-(hydroxymethyl)phenyl)amino)-1-oxo-5-ureidopentan-2-yl)cyclobutane-1,1-dicarboxamide
(S)-4-Nitrophenyl (4-(2-(1-(prop-2-yn-1-ylcarbamoyl)cyclobutane-1-carboxamido)-5-ureidopentanamido)benzyl) carbonate
(S)-4-(2-(1-((5-(2,5-Dioxo-2,5-dihydro-1H-pyrrol-1-yl)pentyl)carbamoyl)cyclobutane-1-carboxamido)-5-ureidopentanamido)benzyl (4-nitrophenyl) carbonate
