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

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

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

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

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

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

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

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

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

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

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