Used in peptide synthesis, particularly in solid-phase peptide synthesis (SPPS), as a protected amino acid derivative. The Fmoc group ensures selective deprotection during synthesis, while the HPO3Bzl group protects the hydroxyl side chain of threonine, preventing unwanted reactions. This compound is essential for creating peptides with phosphorylated threonine residues, which are crucial in studying phosphorylation processes in proteins. It is widely applied in biochemistry and pharmaceutical research for developing peptide-based drugs and studying protein-protein interactions.