4-Oxo-4-(4-(2,3,4-trimethoxybenzyl)piperazin-1-yl)butanoic acid

(2R)-2-{[(1RS,3SR)-3-[({[(9H-fluoren-9-yl)methoxy]carbonyl}amino)methyl]-2,2-difluorocyclopropyl]formamido}-4-(methylsulfanyl)butanoic acid

(2S)-3-(tert-butoxy)-2-({2-[({[(9H-fluoren-9-yl)methoxy]carbonyl}amino)methyl]cyclopropyl}formamido)propanoic acid

2-{2-[({[(9H-fluoren-9-yl)methoxy]carbonyl}amino)methyl]cyclopropaneamido}-1-methylcyclopentane-1-carboxylic acid

rac-2-{1-[(1R,2S)-2-[({[(9H-fluoren-9-yl)methoxy]carbonyl}amino)methyl]cyclopropyl]-N-methylformamido}acetic acid

2-{3-[3-({[(9H-fluoren-9-yl)methoxy]carbonyl}amino)cyclobutaneamido]cyclobutyl}acetic acid

2-{3-[4-({[(9H-fluoren-9-yl)methoxy]carbonyl}amino)-3-hydroxybutanamido]cyclobutyl}acetic acid

(2S)-2-{2-[3-({[(9H-fluoren-9-yl)methoxy]carbonyl}amino)cyclobutyl]acetamido}-3-hydroxypropanoic acid

5-[(3aR,6aS)-hexahydro-1H-furo[3,4-c]pyrrol-5-yl]-4-({[(9H-fluoren-9-yl)methoxy]carbonyl}amino)-5-oxopentanoic acid

3-cyclopentyl-3-[(2R)-2-({[(9H-fluoren-9-yl)methoxy]carbonyl}amino)propanamido]propanoic acid

3-cyclopentyl-3-[2-({[(9H-fluoren-9-yl)methoxy]carbonyl}amino)pent-4-enamido]propanoic acid