H-Arg(NO2)-OBzl p-tosylate salt

H-Arg(NO2)-OBzl p-tosylate salt is a protected L-arginine derivative in which the α-amino group is present as an N-terminal free amino functionality (H-), the guanidinium side chain is nitrated to introduce an NO2-substituted guanidine motif, and the α-carboxyl group is masked as a benzyl ester (OBzl). The p-toluenesulfonate counterion pairs with the basic/charged guanidine region, supporting isolation as a salt and influencing solubility and handling during peptide coupling and intermediate synthesis. The stereogenic center at the α-carbon retains the L-configuration typical of amino acid building blocks, while the benzyl ester and the substituted guanidine provide distinct reactivity windows for controlled deprotection and downstream functionalization. The combination of a protected carboxyl ester, a salt-stabilized cationic side chain, and a nitrated guanidine functionality makes this compound a chiral, peptide-compatible amino acid intermediate suited to derivatization and protected amino acid chemistry workflows.

1. Protected Amino Acids

H-Arg(NO2)-OBzl p-tosylate salt serves as a protected amino acid intermediate for assembling peptide building blocks where benzyl ester masking enables selective C-terminal manipulation and subsequent deprotection strategies. The benzyl ester (OBzl) can be carried through coupling chemistry as a stable carboxyl protecting group, while the nitrated guanidine side chain maintains a strongly basic, cation-associated character that is compatible with salt formation and controlled activation conditions. The p-toluenesulfonate counterion supports reproducible handling of the guanidine-containing functionality during synthesis of N-protected or activated derivatives. The resulting intermediate can be converted into downstream arginine-containing peptide fragments and can feed into iterative amino acid ester-to-amide transformations in fine chemical synthesis.

2. Peptide Coupling Chemistry

H-Arg(NO2)-OBzl p-tosylate salt is applicable to peptide synthesis workflows that require arginine-like side-chain chemistry and controlled protection of the α-carboxyl group. The benzyl ester provides a defined C-terminal protection state for incorporation into peptide coupling sequences, while the nitrated guanidine functionality can influence coupling selectivity and side-chain reactivity during fragment assembly. The salt form helps manage the charged guanidine region, supporting consistent behavior in coupling and purification steps when generating protected peptide analogs. The compound can be used to construct arginine-rich sequences or to prepare protected arginine derivatives for solid-phase or solution-phase peptide assembly where side-chain modification and later unveiling are required.

3. Peptidomimetics And SAR

H-Arg(NO2)-OBzl p-tosylate salt supports peptidomimetic and structure-activity relationship studies by providing a chiral arginine-derived scaffold with a nitrated guanidine motif that can serve as a functional handle for analog generation. The nitrated side chain introduces an additional electron-withdrawing substituent pattern relative to native guanidine, enabling access to modified charge distribution and hydrogen-bonding profiles relevant to receptor or enzyme binding studies. The benzyl ester can be transformed into alternative carboxyl derivatives for library synthesis, while the amino acid stereocenter preserves the spatial arrangement needed for SAR-focused analog comparison. The compound can therefore function as a synthesis input for generating arginine analogs, constrained mimetics, and side-chain-modified fragments used in medicinal chemistry campaigns.

4. Chemical Biology Probes

H-Arg(NO2)-OBzl p-tosylate salt can be employed in chemical biology research where arginine-like, cationic side-chain chemistry is used to probe biomolecular recognition and post-translational modification pathways. The nitrated guanidine functionality may enable targeted reactivity or altered binding interactions compared with unmodified guanidine, and the salt-stabilized form can facilitate conjugation planning when building labeled peptides or affinity reagents. The benzyl ester protection state allows staged conversion to amide or activated ester formats for conjugation to carriers, linkers, or solid supports. The compound's amino acid backbone and stereochemistry make it suitable for constructing probe scaffolds that retain peptide-like geometry while introducing side-chain electronic modulation.

5. Process Chemistry Intermediate

H-Arg(NO2)-OBzl p-tosylate salt is suitable for process chemistry and specialty chemical production as a chiral intermediate that can be routed through protection-state adjustments before final conversion to peptide-grade building blocks. The benzyl ester offers a practical protecting-group strategy for managing carboxyl reactivity during upstream synthesis, while the p-tosylate salt form can improve isolability and handling of the guanidine-containing component on scale. The nitrated guanidine side chain provides a defined functional pattern that can be carried through manufacturing steps and later transformed into alternative arginine-derived functionalities as required by downstream product specifications. The compound can therefore be integrated into industrial intermediate preparation for arginine-containing peptides, peptidomimetics, and functional amino acid derivatives used across chemical manufacturing pipelines.

6. Analytical Standards Development

H-Arg(NO2)-OBzl p-tosylate salt can be used to develop analytical standards and reference materials for monitoring amino acid derivative synthesis, including protected amino acid and peptide intermediate characterization. The combination of benzyl ester protection, nitrated guanidine functionality, and salt counterion yields a distinct mass/fragmentation signature that can support method development for LC-MS, HPLC, and related analytical workflows. The preserved L-configuration at the α-carbon supports stereochemical assignment when chiral chromatographic or derivatization-based analyses are employed to verify amino acid integrity. The compound can serve as a structural benchmark for quantifying conversion of protected arginine intermediates into downstream peptide building blocks and for confirming identity during fine chemical synthesis.

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