[(S)-1-((S)-2-Amino-3-methyl-butyryl)-piperidin-3-yl]-carbamic acid tert-butyl ester

(1R,4R)-[4-((S)-2-Amino-3-methyl-butyrylamino)-cyclohexyl]-ethyl-carbamic acid tert-butyl ester

[(S)-1-((S)-2-Amino-3-methyl-butyryl)-piperidin-3-yl]-isopropyl-carbamic acid tert-butyl ester

[1-((S)-2-Amino-3-methyl-butyryl)-piperidin-3-ylmethyl]-isopropyl-carbamic acid tert-butyl ester

[1-((S)-2-Amino-3-methyl-butyryl)-pyrrolidin-2-ylmethyl]-cyclopropyl-carbamic acid tert-butyl ester

[4-((S)-2-Amino-3-methyl-butyrylamino)-cyclohexyl]-cyclopropyl-carbamic acid tert-butyl ester

(3-tert-Butoxycarbonylamino-pyrrolidin-1-yl)-acetic acid

[3-(tert-Butoxycarbonyl-methyl-amino)-pyrrolidin-1-yl]-acetic acid

[(S)-2-(tert-Butoxycarbonylamino-methyl)-pyrrolidin-1-yl]-acetic acid

[(R)-3-(tert-Butoxycarbonyl-methyl-amino)-piperidin-1-yl]-acetic acid

(1R,4R)-[4-(tert-Butoxycarbonyl-methyl-amino)-cyclohexylamino]-acetic acid