Used in peptide synthesis, particularly in solid-phase peptide synthesis (SPPS) as a building block. It helps in the incorporation of glutamic acid into peptide chains while protecting the amino and carboxyl groups during the synthesis process. The Fmoc group provides temporary protection for the amino group, which can be removed under mild basic conditions, while the tert-butyl ester protects the side chain carboxyl group, which is later removed under acidic conditions. This compound is essential for creating peptides with specific sequences and functionalities, often used in pharmaceutical research and the development of therapeutic peptides.