H-Dap(Boc)-OMe.HCl is a protected derivative of the non-proteinogenic amino acid L-α,β-diaminopropionic acid (Dap). Its chemical structure features a Boc (tert-butoxycarbonyl) group protecting the β-amino functionality and a methyl ester protecting the carboxylic acid group, with the α-amino group remaining as a free amine in its hydrochloride salt form. This specific protection scheme makes it a crucial chiral building block. This compound is primarily employed as a key intermediate in the synthesis of peptides and peptidomimetics, particularly those requiring the incorporation of the diaminopropionic acid scaffold. The Dap residue is valuable for introducing basic side chains or for serving as a branching point in peptide structures. It finds significant application in medicinal chemistry research for developing enzyme inhibitors, antimicrobial peptides, and other bioactive molecules. As a specialty amino acid derivative, it is not a commodity chemical but a high-value reagent for targeted synthesis. Its use is confined to research and development settings, including pharmaceutical and bioconjugation chemistry, where precise control over amino acid stereochemistry and side-chain reactivity is essential.