(R)-N-Fmoc-2-(3'-butyl)glycine is a non-proteinogenic, chiral amino acid derivative. Its structure features an Fmoc (9-fluorenylmethoxycarbonyl) protecting group on the amine functionality and a unique 3-butyl side chain attached to the alpha-carbon, which is in the (R)-configuration. This compound is a solid under standard conditions. This building block is primarily employed in solid-phase peptide synthesis (SPPS) as a specialized amino acid residue. The Fmoc group is a standard, base-labile protecting group that allows for the sequential assembly of peptide chains. The incorporation of the (R)-2-(3'-butyl)glycine residue introduces structural constraints and specific steric or hydrophobic properties into the peptide sequence, which is crucial for modulating the peptide's biological activity, stability (e.g., against enzymatic degradation), and its three-dimensional conformation. It is a key intermediate in the research and development of novel therapeutic peptides and peptidomimetics. As a chiral, non-natural amino acid, it serves as a critical tool in medicinal chemistry for structure-activity relationship (SAR) studies. Its use helps in designing peptides with enhanced potency, selectivity, or improved pharmacokinetic profiles for potential drug candidates targeting various diseases.