Fmoc-Tyr(tBu)-OH is a protected amino acid derivative widely employed in Fmoc-based solid-phase peptide synthesis and serves as a key reagent for the stepwise assembly of peptide chains. Fmoc-Tyr(tBu)-OH can be specifically utilized to synthesize Leu-EnkephalinAmide through solid-phase synthesis in aqueous media and is also used for the generation of amino acid derivatives such as Fmoc-Tyr-OAllyl, highlighting its versatility and importance in peptide chemistry.