(1R,4R)-[4-((S)-2-Amino-propionylamino)-cyclohexyl]-isopropyl-carbamic acid tert-butyl ester

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

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

[1-((S)-2-Amino-3-methyl-butyryl)-piperidin-4-yl]-methyl-carbamic acid tert-butyl ester

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

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

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

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

((R)-3-tert-Butoxycarbonylamino-piperidin-1-yl)-acetic acid

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

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