BOC-D-Phe-OSU is an activated ester derivative of N-(tert-butoxycarbonyl)-D-phenylalanine, widely used in peptide synthesis. The N-hydroxysuccinimide (OSU) group activates the carboxyl moiety, enabling efficient amide bond formation with the amino group of another amino acid or growing peptide chain. The Boc protecting group shields the amino group of D-phenylalanine, preventing side reactions and allowing selective coupling. This reagent is particularly valuable in solid-phase peptide synthesis (SPPS) for the stepwise construction of peptides. Its Boc group is stable under basic coupling conditions but readily removable under mild acidic conditions, making it ideal for producing complex peptides, proteins, chiral compounds, and pharmaceutical intermediates with specific stereochemical requirements.