Fmoc-D-Arg(Mts)-OH

Fmoc-D-Arg(Mts)-OH is a fluorenylmethoxycarbonyl (Fmoc) protected D-arginine derivative featuring an Mts (2,2,5,7,8-pentamethylchroman-6-sulfonyl) side-chain protecting group on the guanidinium moiety. The molecule contains a stereogenic center at the amino acid backbone, with the D-configuration preserved for stereochemically defined peptide assembly. The Fmoc group provides base-labile N-protection for stepwise solid-phase or solution-phase peptide synthesis, while the Mts group masks the strongly basic guanidine functionality to control chemoselectivity during coupling and downstream transformations. The protected guanidinium and carboxylate functionality render the compound a stable chiral amino acid intermediate that can be converted into peptide building blocks and further derivatized for biochemical and materials-oriented research.

1. Peptide Synthesis

Fmoc-D-Arg(Mts)-OH supports peptide building block preparation for automated and manual peptide coupling workflows, where the Fmoc-protected amino terminus enables controlled deprotection and re-coupling cycles. The D-arginine backbone provides a stereochemically defined residue, while the Mts-protected guanidinium side chain suppresses undesired salt formation and side reactions that can occur with unprotected basic residues. The combination of N-Fmoc protection and side-chain guanidine masking facilitates reliable amide bond formation at the α-carboxylate during peptide chain elongation and helps maintain sequence fidelity for Arg-containing peptides. Downstream, deprotection strategies can regenerate the guanidinium functionality for incorporation into cationic peptides, cell-penetrating sequences, and receptor-binding analogs used across peptide science and chemical biology.

2. Chemical Biology

Fmoc-D-Arg(Mts)-OH is suitable for chemical biology studies requiring controlled presentation of arginine-like cationic recognition elements in peptide probes. The guanidinium side chain, protected as Mts, enables stepwise synthesis of peptides that can later be unmasked to restore strong hydrogen-bonding and electrostatic interactions characteristic of arginine. The D-configuration can be used to probe stereochemical effects on binding, protease resistance, and membrane association by constructing D-amino acid-containing molecular tools. The resulting Arg-bearing peptides or conjugation-ready intermediates can be applied to target engagement mapping, affinity probe generation, and mechanistic investigations of biomolecular recognition.

3. Bioconjugation Chemistry

Fmoc-D-Arg(Mts)-OH functions as a protected amino acid precursor for constructing bioconjugation-ready peptide linkers and labeling reagents where guanidinium chemistry must be introduced with chemoselective control. The Mts group stabilizes the side chain during peptide assembly, preventing premature reactions that may complicate conjugation planning when installing dyes, affinity handles, or polymerizable tags. The Fmoc strategy allows orthogonal handling of the peptide N-terminus, supporting controlled generation of a free amine at the desired stage for subsequent coupling to activated esters, isothiocyanates, or maleimide-based systems. Downstream products can serve as linker components for biomolecule labeling, affinity capture constructs, and analytical probes that rely on arginine-mediated solubility and binding behavior.

4. Peptidomimetics And SAR

Fmoc-D-Arg(Mts)-OH can be employed in peptidomimetic construction and structure-activity relationship (SAR) studies where arginine side-chain geometry and charge distribution are tuned via protected amino acid incorporation. The D-arginine stereocenter supports the synthesis of stereochemically defined analog series, enabling systematic evaluation of how inversion of configuration affects binding patterns and stability against enzymatic degradation. The Mts-protected guanidinium enables consistent peptide assembly while preserving the ability to regenerate the native-like cationic group for interaction studies after deprotection. The resulting D-Arg-containing peptide analogs can be used to generate libraries of backbone-modified scaffolds and to support SAR workflows in synthetic organic chemistry and applied molecular design.

5. Pharmaceutical Manufacturing

Fmoc-D-Arg(Mts)-OH is applicable to pharmaceutical manufacturing workflows that require reproducible synthesis of Arg-containing peptide intermediates under controlled protecting-group strategies. The Fmoc group provides a standardized N-protection handle compatible with common peptide synthesis chemistries used to generate defined sequences, while the Mts side-chain protection supports handling of the strongly basic guanidinium functionality during intermediate formation. The stereodefined D-configuration supports the manufacture of stereochemically consistent peptide building blocks for downstream formulation or further synthetic elaboration. The compound can therefore serve as a process-compatible input for producing protected peptide fragments and for preparing intermediates that later undergo deprotection steps to yield cationic Arg residues in the final manufacturing sequence.

6. Process Chemistry Intermediate

Fmoc-D-Arg(Mts)-OH is a chiral amino acid intermediate that can be integrated into process chemistry routes for producing protected Arg-containing fragments with controlled chemoselectivity. The orthogonal protection pattern, combining base-labile Fmoc N-protection with side-chain guanidine masking via Mts, supports stepwise conversion of the amino acid into peptide-coupling-ready forms while minimizing side reactions associated with free guanidinium groups. The protected guanidinium can be carried through multiple synthetic stages, enabling route design that separates coupling, purification, and final deprotection into manageable downstream steps. The resulting intermediates align with fine chemical synthesis practices where stereochemical integrity, protecting-group stability, and predictable functional-group exposure are central to reliable manufacturing of amino acid-derived products.

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