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

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

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

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

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

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

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

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

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

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

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