Fmoc-D-Tle-OH is the Fmoc-protected form of D-tert-leucine, a non-natural D-amino acid used primarily in peptide synthesis. It acts as a protecting group for the amino functionality of D-tert-leucine, ensuring selective reactions during the formation of peptide bonds. This compound is particularly valuable in solid-phase peptide synthesis (SPPS), where it facilitates the stepwise assembly of peptides incorporating this unusual amino acid to enhance stability or bioactivity. The Fmoc (9-fluorenylmethyloxycarbonyl) group can be easily removed under mild basic conditions, such as with piperidine, making it a preferred choice for synthesizing complex peptides and proteins. Its applications extend to pharmaceutical development, bioactive peptides, and research in biochemistry and molecular biology.