(R)-3-[((S)-2-Amino-propionyl)-ethyl-amino]-piperidine-1-carboxylic acid tert-butyl ester

3-[((S)-2-Amino-3-methyl-butyryl)-cyclopropyl-amino]-piperidine-1-carboxylic acid tert-butyl ester

4-{[((S)-2-Amino-3-methyl-butyryl)-isopropyl-amino]-methyl}-piperidine-1-carboxylic acid tert-butyl ester

3-(Carboxymethyl-amino)-pyrrolidine-1-carboxylic acid benzyl ester

(4-Benzyloxycarbonylamino-cyclohexylamino)-acetic acid

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

3-[(Carboxymethyl-ethyl-amino)-methyl]-pyrrolidine-1-carboxylic acid benzyl 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