Boc-β-Ala-Osu, or N-(tert-butoxycarbonyl)-β-alanine N-hydroxysuccinimide ester, is an activated ester reagent widely used in peptide synthesis. It enables the efficient and selective coupling of the Boc-protected β-alanine residue to the N-terminal amine of amino acids or growing peptide chains, facilitating stepwise peptide assembly. This compound is especially valuable in solid-phase peptide synthesis (SPPS), where it helps prevent unwanted side reactions, improves coupling yields, and supports the construction of complex peptides. The Boc protecting group on the β-alanine amine ensures orthogonality and can be readily removed under mild acidic conditions (e.g., TFA in DCM) without affecting other protections. Due to these properties, Boc-β-Ala-Osu is a preferred reagent in organic synthesis, medicinal chemistry, and the development of peptide-based drugs, bioactive molecules, and other advanced organic compounds.