H-Arg(Pbf)-OMe · HCl

H-Arg(Pbf)-OMe · HCl is an arginine-derived methyl ester hydrochloride featuring the canonical α-amino acid backbone with a stereogenic center and a side-chain guanidinium functionality masked as a Pbf (2,2,4,6,7-pentamethyldihydrobenzofuran) protected guanidine. The compound is present as the hydrochloride salt, which supports handling of the ester-bearing, N-protected amino acid while maintaining controlled reactivity of the protected side chain. The methyl ester (OMe) provides a C-terminal protected form compatible with peptide coupling workflows, whereas the Pbf group is designed to withstand common acylation conditions and to enable later deprotection for free guanidinium display. The combination of stereochemistry, salt formation, and orthogonal protecting-group behavior makes the material a practical chiral intermediate for arginine incorporation and subsequent side-chain functional transformations in peptide and peptidomimetic synthesis.

1. Protected Arginine Peptide Synthesis

H-Arg(Pbf)-OMe · HCl is used in peptide building-block preparation where arginine side-chain guanidinium must remain masked during amide bond formation. The Pbf-protected guanidine and the α-amino group enable peptide coupling chemistry while limiting undesired side reactions from the strongly basic side chain. The methyl ester at the carboxyl terminus supports C-terminal protection during stepwise elongation, and subsequent ester hydrolysis or conversion can be applied to generate the appropriate coupling partner. The hydrochloride form can facilitate consistent salt-state handling during synthesis and downstream workup, supporting the construction of peptides and peptide fragments that require orthogonal deprotection strategies.

2. Peptidomimetic And SAR Studies

H-Arg(Pbf)-OMe · HCl supports peptidomimetic construction and structure-activity relationship studies by providing a stereodefined arginine unit with a protected guanidine handle for later unveiling. The guanidine functionality can be revealed under conditions compatible with the Pbf group, allowing controlled generation of cationic recognition motifs in bioactive analogs. The protected amino acid ester format can be converted into alternative termini or linked into constrained scaffolds, enabling systematic variation of charge presentation and hydrogen-bonding geometry. The chiral backbone and orthogonal protection pattern make it suitable for generating arginine-containing analog libraries where side-chain deprotection timing is a key design variable.

3. Chemical Biology Bioconjugation

H-Arg(Pbf)-OMe · HCl is applicable to chemical biology workflows that require installation of arginine-rich motifs for conjugation chemistry and biomolecule labeling. The Pbf-protected guanidine can be kept inert during coupling to activated linkers or scaffold components, while later deprotection can restore the free guanidinium for electrostatic interactions, binding assays, or conjugate maturation. The methyl ester can be transformed into an amide, activated ester, or other electrophile-bearing derivative to enable attachment to peptides, polymers, or carrier proteins under controlled conditions. The hydrochloride salt form can help maintain reproducible ionic character during intermediate preparation, supporting downstream assembly of arginine-functional conjugates used in biochemical research.

4. Process Chemistry Intermediate Preparation

H-Arg(Pbf)-OMe · HCl is suitable for process chemistry intermediate preparation where protecting-group robustness and predictable deprotection behavior are required for manufacturing-scale peptide inputs. The Pbf group on the guanidine is engineered to tolerate peptide coupling conditions, while the methyl ester provides a defined C-terminal protection state that can be converted to acids or activated derivatives as process steps progress. Hydrochloride salt formation supports handling of the amino acid intermediate with controlled basicity, which can influence solubility and filtration behavior in industrial workflows. The compound's stereodefined arginine configuration and orthogonal protection profile can be leveraged to streamline downstream synthesis of protected arginine-containing intermediates used in fine chemical production.

5. Pharmaceutical Manufacturing Peptide Inputs

H-Arg(Pbf)-OMe · HCl is used as a protected arginine input for pharmaceutical manufacturing contexts involving peptide synthesis and peptide-derived intermediate generation. The combination of an N-protected amino acid ester and Pbf-protected guanidine supports sequential coupling steps while maintaining side-chain integrity until the intended deprotection stage. The methyl ester terminus can be converted into carboxylic acid or other activated forms required for subsequent fragment coupling, enabling controlled build-up of peptide sequences that include cationic arginine residues. The hydrochloride salt form can assist in consistent intermediate handling during scale-up operations, supporting reliable preparation of peptide building blocks and downstream quality-relevant intermediates.

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