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

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

3-((S)-2-Amino-propionylamino)-piperidine-1-carboxylic acid tert-butylester

[2-((S)-2-Amino-propionylamino)-cyclohexyl]-carbamic acid tert-butyl ester

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

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

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

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

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

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

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