Used in peptide synthesis as a protected amino acid building block, particularly in the preparation of structurally constrained peptides. The Fmoc group allows for solid-phase synthesis by enabling orthogonal protection strategies, making it compatible with base-labile linkers. The cis configuration and proline scaffold introduce conformational rigidity, which is valuable in designing peptides with enhanced stability, receptor selectivity, or improved pharmacokinetic profiles. Commonly applied in medicinal chemistry for developing bioactive peptides, enzyme inhibitors, and peptidomimetics.