[1-((S)-2-Amino-propionyl)-piperidin-4-yl]-cyclopropyl-carbamic acid benzyl ester

[1-((S)-2-Amino-3-methyl-butyryl)-piperidin-4-ylmethyl]-methyl-carbamic acid benzyl ester

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

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

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

((R)-3-Benzyloxycarbonylamino-piperidin-1-yl)-acetic acid

[3-(Benzyloxycarbonyl-methyl-amino)-piperidin-1-yl]-acetic acid

{2-[(Benzyloxycarbonyl-methyl-amino)-methyl]-piperidin-1-yl}-acetic acid

{3-[(Benzyloxycarbonyl-ethyl-amino)-methyl]-pyrrolidin-1-yl}-acetic acid

[(S)-3-(Benzyloxycarbonyl-isopropyl-amino)-piperidin-1-yl]-acetic acid

(1R,4R)-[4-(Benzyloxycarbonyl-isopropyl-amino)-cyclohexylamino]-acetic acid