Boc-Gly-ONp is an activated ester derivative of N-(tert-butoxycarbonyl)glycine, featuring a p-nitrophenyl group that facilitates nucleophilic acyl substitution. It is primarily employed in peptide synthesis to incorporate the glycine residue into peptide chains. The Boc group serves as an amino-protecting moiety, shielding the N-terminus from unwanted reactions during coupling, while the active ester enhances reactivity of the carboxylic acid for efficient amide bond formation with free amino groups. This compound is versatile for both solution-phase and solid-phase peptide synthesis (SPPS), supporting the sequential assembly of peptides with high yield and purity. Additionally, it is used in preparing peptide conjugates, derivatives, and biomolecular constructs for research in organic synthesis, biochemistry, and medicinal chemistry, particularly in drug development. The Boc protection is orthogonally removable under mild acidic conditions post-coupling, ensuring compatibility with diverse synthetic strategies.