Boc-α-Propyl-DL-proline is a derivative of the unnatural amino acid α-propyl-DL-proline, featuring a tert-butoxycarbonyl (Boc) protecting group on the N-terminal amino group. It serves as a key building block in solid-phase peptide synthesis (SPPS), enabling the incorporation of the α-propylproline residue into peptide chains. The propyl substituent at the α-position introduces steric and conformational constraints, which are valuable for designing peptides with specific structures and biological activities. This compound is widely used in pharmaceutical research and development for creating peptide-based therapeutics, as well as in academic studies exploring peptide folding, stability, and interactions.