Boc-D-Asp(OtBu)-OH is a protected derivative of D-aspartic acid, with a Boc (tert-butoxycarbonyl) protecting group on the α-amino group and a tert-butyl (OtBu) ester on the side-chain carboxylic acid. It serves as a key building block in peptide synthesis, particularly solid-phase peptide synthesis (SPPS), to incorporate D-Asp residues while preventing unwanted side reactions during peptide bond formation. The protecting groups provide stability and allow for selective deprotection under mild acidic conditions, ensuring the correct sequence and structure of complex peptides. This compound is valuable in pharmaceutical research, drug development, and the synthesis of biologically active peptides and peptidomimetics.