Fmoc-D-Arg(Pbf)-OPfp

Fmoc-D-Arg(Pbf)-OPfp is an Fmoc-protected D-arginine derivative bearing a Pbf (2,2,4,6,7-pentamethylchroman-6-sulfonyl) side-chain protection on the guanidinium group and an OPfp active ester at the carboxyl terminus. The stereogenic center at the D-arginine backbone fixes the configuration for stereochemically defined peptide coupling, while the guanidinium functionality is masked to prevent undesired salt formation or side reactions during fragment assembly. The OPfp leaving group enables acyl transfer under peptide-synthesis-compatible conditions, and the Fmoc group supports orthogonal N-terminal deprotection strategies for stepwise solid-phase or solution-phase construction. The combination of a protected guanidine, a base-labile Fmoc group, and an activated carboxylate makes the compound a structured intermediate for peptide building block preparation and downstream derivatization in amino acid chemistry.

1. Peptide Coupling

Fmoc-D-Arg(Pbf)-OPfp is used in peptide synthesis workflows where activated carboxylates are required for reliable amide bond formation. The OPfp ester activates the carboxyl group for nucleophilic acyl substitution, while the Fmoc group provides an N-protection handle that can be removed under standard base conditions to expose a coupling-ready amine. The Pbf-protected guanidinium side chain preserves arginine-like polarity without interfering with coupling steps, enabling controlled incorporation of D-Arg residues into peptide sequences. The resulting D-arginine-containing peptide intermediates can be carried forward to generate peptide analogs, stereodefined scaffolds, and protected peptide fragments for further purification and characterization.

2. Unnatural Amino Acid Incorporation

Fmoc-D-Arg(Pbf)-OPfp serves in chemical biology and peptidomimetic research that requires stereochemically defined incorporation of D-amino acids. The D-configuration at the α-carbon and the protected guanidine side chain allow the building of peptides with altered backbone stereochemistry while maintaining compatibility with peptide coupling chemistry. The orthogonal protection pattern, combining Fmoc on the α-amine and Pbf on the side-chain guanidine, supports sequential assembly followed by later deprotection to reveal the cationic functionality. Downstream peptide analog construction can leverage the exposed guanidinium for receptor-binding mimicry, binding-site probing, and structure-activity relationship studies that depend on stereochemical control.

3. Bioconjugation Chemistry

Fmoc-D-Arg(Pbf)-OPfp is applicable to bioconjugation and biomolecule modification strategies that utilize arginine side-chain chemistry and activated ester reactivity. The OPfp group can participate in acylation steps to form stable amide linkages with nucleophilic partners, while the Pbf protection helps manage guanidinium reactivity during the conjugation setup. The Fmoc group can be used as a temporary protection element to control reaction order, enabling preparation of conjugation-ready intermediates before final deprotection of the side-chain functionality. The resulting D-arginine-containing conjugates may be used as labeled probes, affinity handles, or scaffold components where guanidinium-driven interactions are needed in a stereodefined manner.

4. Protected Amino Acid Synthesis

Fmoc-D-Arg(Pbf)-OPfp is relevant to synthetic organic chemistry as a protected amino acid derivative for constructing well-defined intermediates in multi-step manufacturing routes. The molecule integrates three functional design elements that map to process-friendly protection logic: Fmoc for base-labile N-protection, Pbf for side-chain guanidine protection, and OPfp for carboxyl activation. The controlled reactivity profile helps minimize side reactions associated with free guanidinium salts and unactivated carboxylic acids during intermediate formation and purification. The compound can be employed to prepare protected peptide building blocks and activated fragments that feed into larger peptide or peptidomimetic synthesis campaigns used in fine chemical production.

5. Process Chemistry Intermediate

Fmoc-D-Arg(Pbf)-OPfp is suitable for process chemistry intermediate preparation where activated amino acid derivatives are used to streamline coupling steps and reduce variability across batch syntheses. The OPfp ester functionality supports consistent acyl transfer behavior for forming peptide bonds, while the stable protection scheme (Fmoc and Pbf) helps maintain chemoselectivity during sequential assembly operations. The stereochemical integrity of the D-arginine center supports reproducible generation of D-Arg-containing products that require defined stereopurity for downstream analytical comparability. The compound's role as an activated, protected amino acid intermediate supports scalable production of protected peptides and peptide fragments used in research-grade manufacturing and specialized chemical supply chains.

1. Myotropic activity and immunolocalization of selected neuropeptides of the burying beetle Nicrophorus vespilloides (Coleoptera: Silphidae)

2. Crystal Structure of BamB from Pseudomonas aeruginosa and Functional Evaluation of Its Conserved Structural Features

3. The effect of B-type allatostatin neuropeptides on crosstalk between the insect immune response and cold tolerance

4. Myotropic activity of allatostatins in tenebrionid beetles

5. Autoinhibition and phosphorylation-induced activation of phospholipase C-γ isozymes