Cationic amino acids, such as arginine and lysine, are important constituents of biologically active peptides, 1 and 2 and play a significant role in the binding of peptide substrates and their molecular targets. Homologues of these cationic amino acids are also valuable tools in the preparation of peptidic enzyme inhibitors and, in particular, for probing enzyme active site pockets in ligand based drug design. 3 For example, (S)-homolysine 1 (shown as the di-HCl salt), a ...