4-[((S)-2-Amino-propionyl)-isopropyl-amino]-piperidine-1-carboxylic acid tert-butyl ester

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

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

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

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

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

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

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

(2-Benzyloxycarbonylamino-cyclohexylamino)-acetic acid

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

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