Used in peptide synthesis as a protected amino acid building block. The Boc group protects the amine functionality, while the benzyl (Bzl) group protects the side chain hydroxyl of homoserine. This allows selective coupling at the carboxylic acid during solid-phase or solution-phase peptide assembly. After incorporation into the peptide chain, the Boc group can be removed under mild acidic conditions without affecting the benzyl protection. The benzyl group is later removed in the final deprotection step, typically via hydrogenolysis or strong acid like HF, to yield the free hydroxyl group in the target peptide. Commonly used in the synthesis of complex bioactive peptides where side chain protection is required.