N-Boc-cis-4-N-Fmoc-amino-L-proline is a doubly protected derivative of cis-4-amino-L-proline, widely used in peptide synthesis, particularly in solid-phase peptide synthesis (SPPS). The Boc (tert-butoxycarbonyl) group protects the α-nitrogen of the proline ring, while the Fmoc (fluorenylmethyloxycarbonyl) group protects the side-chain amino group at the cis-4-position. This orthogonal dual protection allows for selective deprotection during the synthesis process, enabling the stepwise construction of complex peptides incorporating this modified amino acid. Its application is crucial in the synthesis of proline-rich or modified peptides, which are often found in bioactive molecules and proteins. Additionally, it is employed in the development of peptidomimetics and pharmaceutical compounds, where precise control over amino acid incorporation is essential. The compound’s stability and compatibility with standard peptide synthesis protocols make it a valuable tool in medicinal chemistry and drug discovery research.