Fmoc-D-Arg(Boc)2-OH

Fmoc-D-Arg(Boc)2-OH is a protected D-arginine derivative bearing an Fmoc group on the alpha-amino functionality and two Boc protecting groups on the guanidino side chain, yielding a doubly protected, chiral amino acid building block. The molecule contains a stereogenic center at the alpha carbon, a carboxylic acid for C-terminal activation, and a highly basic guanidinium motif that is masked by Boc groups to suppress undesired side reactions during peptide assembly. The Fmoc carbamate is designed for base-labile removal, while the Boc groups are acid-labile, creating an orthogonal protection scheme that supports sequential deprotection and controlled coupling. The resulting reactivity profile is tailored for peptide coupling chemistry and for downstream conversion into arginine-containing peptides, protected intermediates, or guanidine-bearing analogs after selective deprotection.

1. Peptide Synthesis

Fmoc-D-Arg(Boc)2-OH is used in solid-phase peptide synthesis and related peptide building workflows where orthogonal protecting groups are required for arginine incorporation. The Fmoc group enables standard base-mediated deprotection to reveal the N-terminus for iterative amide bond formation, while the Boc-protected guanidino functions prevent side-chain participation and maintain compatibility with coupling reagents. The free carboxylic acid supports activation and coupling to growing peptide chains, and the D-configuration provides access to stereochemically defined arginine analogs for peptide library construction. Guanidine unmasking after assembly can be applied to generate arginine-rich sequences and to study how D-amino acid stereochemistry influences folding, solubility, and sequence-dependent interactions in peptide science.

2. Protected Amino Acids

Fmoc-D-Arg(Boc)2-OH functions as a protected amino acid intermediate for N-protected and side-chain-protected arginine chemistry in synthetic organic workflows. The Fmoc carbamate stabilizes the alpha-amino group under peptide-coupling conditions, whereas the dual Boc protection on the guanidino moiety suppresses nucleophilicity and minimizes salt formation or undesired acylation during intermediate handling. The orthogonality between base-labile Fmoc and acid-labile Boc groups supports stepwise deprotection strategies, enabling controlled generation of either an N-terminal amine or a guanidine-bearing side chain at selected stages. The compound can therefore be employed for protected amino acid synthesis, intermediate preparation for solution-phase peptide assembly, and preparation of guanidine-containing fragments used in larger scaffold construction.

3. Bioconjugation Chemistry

Fmoc-D-Arg(Boc)2-OH can be applied to bioconjugation and chemical biology workflows that require incorporation of arginine-like cationic motifs while preserving orthogonal protection during synthesis. The masked guanidino groups allow the amino acid to be processed through peptide coupling and purification steps without premature side-chain reactivity, and subsequent guanidine deprotection can furnish a strongly basic handle for electrostatic interactions, affinity capture, or charge-tuned conjugate design. The D-amino acid stereochemistry can be leveraged to modulate protease resistance and conformational preferences in conjugated peptides, peptidomimetics, or labeling reagents. Downstream unmasking yields guanidine-bearing conjugation components compatible with peptide-based linkers and biomolecule-modifying constructs used in analytical and research settings.

4. Peptidomimetics And SAR Studies

Fmoc-D-Arg(Boc)2-OH serves as a chiral building block for peptidomimetic construction and structure-activity relationship studies where arginine side-chain geometry and stereochemistry affect molecular recognition. The Fmoc-protected alpha-amino group supports controlled assembly of peptide-like backbones, while the Boc-protected guanidine enables incorporation of cationic pharmacophore elements without interfering with coupling chemistry. The D-configuration at the alpha carbon provides access to stereodefined analogs that can be compared against L-arginine-containing counterparts to evaluate how stereochemistry influences receptor binding, membrane association, or aggregation behavior in SAR panels. Resulting arginine-containing analogs can be utilized as research-grade scaffolds for mechanistic studies, assay development, and iterative medicinal chemistry refinement.

5. Pharmaceutical Manufacturing Intermediates

Fmoc-D-Arg(Boc)2-OH is suitable for pharmaceutical intermediate preparation and process chemistry steps that require reproducible, protected amino acid inputs for peptide or peptide-like manufacturing routes. The compound's orthogonal protection pattern aligns with common manufacturing logic for protecting-group management, where Fmoc deprotection and Boc removal can be scheduled to match purification and coupling stages. The presence of a carboxylic acid enables standardized activation and coupling to produce defined arginine-containing segments, and the protected guanidino side chain supports handling under conditions that would otherwise promote side reactions for free guanidines. Downstream deprotection yields guanidine-bearing peptide intermediates that can be further transformed into drug substance precursors, analytical reference materials, or processable building blocks for specialty chemical production.

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