Fmoc-Dap(Mtt)-OH is widely used in peptide synthesis, particularly in solid-phase peptide synthesis (SPPS). Its primary application is as a building block for introducing the amino acid diaminopropionic acid (Dap) into peptide chains. The Fmoc (9-fluorenylmethoxycarbonyl) group protects the amino group during synthesis, while the Mtt (4-methyltrityl) group provides selective protection for the side chain amine of Dap. This allows for precise control over the incorporation of Dap into peptides, especially in cases where selective deprotection is required for further modifications. The compound is particularly useful in the synthesis of complex peptides, such as those used in drug development, where specific functional groups need to be introduced or protected. Its stability under standard SPPS conditions and the ability to selectively remove the Mtt group make it a valuable tool in peptide chemistry.