Z-D-PHE-OSU, also known as N-(Benzyloxycarbonyl)-D-phenylalanyl N-succinimidyl ester, is a protected D-phenylalanine derivative used as an active ester in peptide synthesis. It enables the efficient formation of peptide bonds by reacting its pre-activated carboxyl group with the amino group of free amino acids or the N-terminus of growing peptide chains, incorporating the Z-protected D-Phe residue. This reagent is essential in the pharmaceutical industry for synthesizing peptide-based therapeutics and in biochemical research for investigating protein structures and functions. It is also utilized in the preparation of modified peptides and peptidomimetics, supporting drug discovery efforts. Due to its high stability and reactivity, Z-D-PHE-OSU is a preferred choice in solid-phase peptide synthesis, delivering high yields and product purity.