Fmoc-Tyr(But)-OSu is a derivative of tyrosine, an important amino acid commonly utilized in peptide synthesis and organic chemistry. The Fmoc (9-fluorenylmethyloxycarbonyl) group, in combination with the tert-butyl (But) ester and N-hydroxysuccinimide (OSu) functionality, provides stability and protection for specific functional groups during chemical reactions, enabling controlled synthesis of complex molecules. This compound is widely employed in research, pharmaceutical development, and various organic synthetic processes due to its versatility and compatibility with diverse synthetic protocols.