Used in solid-phase peptide synthesis as a chiral building block for incorporating structurally constrained amino acid residues into peptides. The Fmoc group allows for orthogonal protection, enabling stepwise assembly under mild basic conditions. The propylenyl side chain introduces hydrophobicity and steric hindrance, which can enhance peptide stability, influence conformation, and improve binding selectivity in bioactive peptides. Commonly applied in the development of peptidomimetics and pharmaceutical research targeting enzyme inhibitors or receptor modulators.