Used in peptide synthesis as a protected amino acid building block, enabling the incorporation of a constrained cyclobutane moiety into peptide chains. The Fmoc group allows for mild base-labile protection, compatible with solid-phase synthesis strategies. Its rigid four-membered ring structure introduces conformational restraint, which can enhance peptide stability, improve receptor selectivity, or modulate biological activity in medicinal chemistry applications. Commonly employed in the development of peptidomimetics and bioactive molecules where backbone or side chain geometry influences function.