This chemical is a protected dipeptide derivative featuring an ester linkage, primarily used in peptide synthesis, particularly in solid-phase peptide synthesis (SPPS) methods. It consists of N-[(9H-fluoren-9-yl)methoxy]carbonyl-L-isoleucine (Fmoc-L-Ile) esterified via its carboxylic acid to the side-chain hydroxyl group of N-(tert-butoxycarbonyl)-L-threonine (Boc-L-Thr). The Fmoc group protects the α-amine functionality of L-isoleucine, and the Boc group protects the α-amine of L-threonine, while the threonine side-chain hydroxyl is incorporated into the ester linkage. This orthogonal protection strategy enables selective deprotection during the stepwise assembly of peptides, ensuring precise control over the sequence and modifications. It is commonly employed in the production of therapeutic peptides, research peptides, and peptide-based drugs, where high purity and specific sequences are critical. Its use is also prevalent in biochemistry and pharmaceutical research for studying protein interactions and developing novel peptide-based treatments.