This compound is widely used in peptide synthesis as a protecting group for glutamic acid. It helps in preventing unwanted side reactions during the assembly of peptide chains. The Boc (tert-butyloxycarbonyl) group protects the amino group, while the OtBu (tert-butyl ester) group protects the carboxyl group of glutamic acid. The OSu (N-hydroxysuccinimide ester) moiety makes it highly reactive towards amino groups, facilitating efficient coupling with other amino acids or peptides. This reagent is particularly useful in solid-phase peptide synthesis (SPPS) and solution-phase synthesis, ensuring high yield and purity of the final peptide product. Its stability and ease of removal under mild acidic conditions make it a preferred choice in peptide chemistry.