Boc-Arg(Pbf)-OH is a protected form of the amino acid arginine, used as a key building block in peptide synthesis, particularly in solid-phase peptide synthesis (SPPS). The Boc (tert-butoxycarbonyl) group protects the α-amino group, while the Pbf (2,2,4,6,7-pentamethyl-dihydrobenzofuran-5-sulfonyl) group protects the guanidino side chain of arginine. This dual protection ensures selective coupling reactions at the free carboxylic acid group during peptide chain assembly, preventing unwanted side reactions. The protecting groups are stable under standard peptide coupling conditions but can be orthogonally removed under specific deprotection conditions (e.g., acid for Boc, TFA for Pbf). It is commonly employed in the production of peptides for pharmaceutical research, including therapeutic peptides and peptidomimetics, making it a versatile reagent in peptide chemistry.