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

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

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

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

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

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

{3-[(tert-Butoxycarbonyl-ethyl-amino)-methyl]-piperidin-1-yl}-acetic acid

{2-[(tert-Butoxycarbonyl-ethyl-amino)-methyl]-piperidin-1-yl}-acetic acid

[4-(tert-Butoxycarbonyl-isopropyl-amino)-piperidin-1-yl]-acetic acid

{2-[(tert-Butoxycarbonyl-cyclopropyl-amino)-methyl]-piperidin-1-yl}-acetic acid

[(S)-1-(2-Hydroxy-ethyl)-piperidin-3-yl]-carbamic acid benzyl ester