4-[((S)-2-Amino-3-methyl-butyrylamino)-methyl]-piperidine-1-carboxylic acid tert-butyl ester

(1R,4R)-[(4-Benzyloxycarbonylamino-cyclohexyl)-ethyl-amino]-acetic acid

3-(Carboxymethyl-isopropyl-amino)-piperidine-1-carboxylic acid benzyl ester

3-[(Carboxymethyl-isopropyl-amino)-methyl]-piperidine-1-carboxylic acid benzyl ester

(R)-3-(Carboxymethyl-cyclopropyl-amino)-piperidine-1-carboxylic acid benzyl ester

4-(Carboxymethyl-cyclopropyl-amino)-piperidine-1-carboxylic acid benzyl ester

[(2-Benzyloxycarbonylamino-cyclohexyl)-cyclopropyl-amino]-acetic acid

3-{[(2-Hydroxy-ethyl)-methyl-amino]-methyl}-piperidine-1-carboxylic acid benzyl ester

(S)-3-[(2-Hydroxy-ethyl)-methyl-amino]-piperidine-1-carboxylic acid benzyl ester

3-[Ethyl-(2-hydroxy-ethyl)-amino]-piperidine-1-carboxylic acid benzyl ester

4-[Ethyl-(2-hydroxy-ethyl)-amino]-piperidine-1-carboxylic acid benzyl ester