Used in solid-phase peptide synthesis to introduce a protected N-methyl lysine residue into peptide chains. The Fmoc group allows for mild base deprotection while the Boc group protects the side-chain amine, ensuring selective reactivity during elongation. Its N-methylated structure enhances peptide stability against proteolytic degradation, making it valuable in developing therapeutic peptides with improved metabolic stability. Commonly applied in the synthesis of complex peptides, including those with constrained conformations or designed for drug discovery.