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Boc-Arg(Tos)-OH, systematically named Nα‑tert‑butyloxycarbonyl‑Nω‑(p‑toluenesulfonyl)‑L‑arginine (CAS 13836-37-8), is a fully protected derivative of the essential amino acid L‑arginine. The molecule consists of three functional components: the N‑terminal α‑amino group is protected by a Boc (tert‑butyloxycarbonyl) group which is stable under basic coupling conditions and is quantitatively removed by TFA during SPPS cycles; the side‑chain guanidino function is protected by a tosyl (p‑toluenesulfonyl) group; and the C‑terminal carboxylic acid remains free for peptide bond formation. The molecular formula is C₁₈H₂₈N₄O₆S, with a molecular weight of 428.50 g/mol.

This orthogonal protection strategy — with the Boc group acid‑labile and the Tos group stable under all SPPS coupling conditions while being cleanly removed during the final HF cleavage step — makes Boc-Arg(Tos)-OH the preferred N‑Boc building block for introducing arginine residues into growing peptide chains. Compared to the alternative Mtr‑based protection strategy, the Tos group offers superior stability during chain elongation and completely avoids the incomplete deprotection issues that commonly arise with Mtr‑based arginine analogs. It is compatible with standard activating reagents (DCC, HATU, HBTU, PyBOP) and is widely used in both manual SPPS, fully automated peptide synthesizers, and large‑scale solution‑phase peptide synthesis for generic APIs.

Market Demand and Core Applications

Global peptide synthesis market is projected to grow from USD 746.7 million in 2025 to USD 1,640.5 million by 2034, registering a strong CAGR of 9.39%, largely driven by the growth of peptide therapeutics, increasing demand for custom peptides in drug discovery, and ongoing development of peptide libraries for high‑throughput screening. As the global peptide therapeutics market expands across GLP‑1 agonists, peptide vaccines, antimicrobial peptides, and peptide‑drug conjugates, the demand for high‑quality arginine building blocks — including Boc-Arg(Tos)-OH — continues to grow at a corresponding pace.

Core Applications

1. Boc Solid‑Phase Peptide Synthesis (SPPS) — ≈70‑75% of total consumption.
Boc-Arg(Tos)-OH is the standard building block for introducing arginine residues into peptide chains using traditional Boc/Bzl SPPS. A key advantage of the Tos group over Mtr protection is its stability during chain assembly: Mtr groups can partially cleave under repeated TFA exposures, leading to side reactions and reduced yields, whereas the Tos group remains intact throughout all coupling and deprotection cycles and is quantitatively removed only during the final anhydrous HF cleavage step. The compound is fully compatible with standard activating reagents and is used extensively in both manual SPPS workflows and fully automated peptide synthesizers, as well as in large‑scale solution‑phase synthesis for generic peptide APIs and high‑volume industrial production campaigns.

2. Peptide‑Based Drug Development — Core Demand Driver.
Boc-Arg(Tos)-OH serves as a key building block for active pharmaceutical ingredients of peptide therapeutics, including glucagon‑like peptide‑1 (GLP‑1) agonists (semaglutide, liraglutide), peptide antibiotics (polymyxin B, colistin), peptide hormones and their analogs, renin inhibitors, HIV protease inhibitors, and custom peptide vaccine synthesis for infectious diseases and oncology indications. In all of these applications, correctly incorporating multiple arginine residues in defined positions is critical for maintaining biological activity, membrane penetration capability, and proper tertiary folding.

3. Antibody‑Drug Conjugate (ADC) and Peptide‑Drug Conjugate (PDC) Development.
Boc-Arg(Tos)-OH is an essential building block in both bioconjugation processes and the construction of complex peptide-based drug delivery systems. During antibody‑drug conjugate assembly, the compound ensures that arginine residues are precisely placed within linker peptides, while in peptide‑drug conjugate research it enables the development of targeted therapeutics with enhanced selectivity and reduced systemic toxicity.

4. Diagnostic Reagents and Clinical Assay Development.
The compound is employed as a key reagent in diagnostic assays that require specific arginine‑containing peptides for binding interactions. Applications include ELISA development, lateral flow immunoassays that rely on arginine‑rich peptide capture probes, and rapid point‑of‑care tests where arginine‑mediated binding ensures diagnostic accuracy and specificity. The stable, fully protected structure of Boc-Arg(Tos)-OH enables high reproducibility in the manufacturing of these critical peptide-based diagnostic tools.

5. Research on Protein‑Protein Interactions and Cellular Signaling.
Boc-Arg(Tos)-OH is a critical research tool for investigating arginine‑dependent protein‑protein interactions involved in numerous cellular signaling pathways. Its use has been documented in studies of enzyme inhibition mechanisms, cellular signaling cascades where arginine residues play essential roles, metabolic pathways and potential therapeutic targets, as well as the role of arginine residues in transcription factors and DNA‑binding proteins.

Major Market Participants and Supply Landscape

The global supply system for Boc-Arg(Tos)-OH includes Sigma‑Aldrich (Merck KGaA), BOC Sciences, Chem‑Impex, Alfa Chemistry, EvitaChem, Combi‑Blocks, and a range of specialized manufacturers based in China. The growing outsourcing of peptide API production to Asian CROs and CDMOs has significantly expanded the procurement of high‑purity Boc-Arg(Tos)-OH, particularly from Chinese suppliers that offer cost‑effective yet high‑quality production.

Shanghai XinChem Co., Ltd. is a leading supplier of high‑purity Boc-Arg(Tos)-OH (CAS 13836-37-8), with a fully integrated, quality‑controlled supply chain that meets rigorous pharmaceutical specifications.

Available purity grades:

≥99.5% (chiral HPLC) — research grade / high‑purity grade
≥98% (HPLC) — industrial grade / peptide synthesis grade

Key quality specifications:

White to off‑white crystalline powder, impurities including D‑enantiomer ≤0.5%, moisture <0.5% (by KF titration), specific optical rotation [α]²⁰ᴰ = −3.5 ± 1 ° (c = 4 in DMF), melting point ~90 °C (with decomposition).

Storage, Stability and Regulatory Considerations

Boc-Arg(Tos)-OH is stable for at least 24 months when stored at 2‑8 °C in a tightly sealed, dry, light‑protected container, kept away from strong oxidizers and strong bases. The compound is not classified as a hazardous material for transport (non‑hazmat) and is not DEA‑regulated. In the European Union, the compound is subject to REACH regulations; in the United States, it is TSCA listed for research use; in China, it is listed in the Inventory of Existing Chemical Substances (IECSC).

Future Outlook and Market Growth Drivers

The Boc-Arg(Tos)-OH market will be primarily driven by the continued expansion of the global peptide therapeutics industry, the scale‑up of generic peptide API manufacturing, the growing adoption of Boc/Bzl SPPS for constructing long and complex peptide sequences, the rapid expansion of Asian CRO/CDMO sectors providing intermediates to global pharmaceutical companies, and its increasing applications in ADC development and peptide‑based diagnostic reagents.

Shanghai XinChem Co., Ltd. is ideally positioned to serve the rising demand with high‑quality Boc-Arg(Tos)-OH.

Shanghai XinChem Co., Ltd.

As a world‑leading supplier of Boc‑protected amino acids and peptide building blocks, Shanghai XinChem Co., Ltd. (XinChem) has always focused on the innovative needs of the peptide therapeutics, CRO/CDMO, and generic API manufacturing industries. Relying on core advantages in Boc‑chemistry and large‑scale heterocyclic synthesis, we provide high‑quality Boc-Arg(Tos)-OH (Nα‑tert‑butyloxycarbonyl‑Nω‑(p‑toluenesulfonyl)‑L‑arginine, CAS 13836-37-8) to global customers.

1. Technical Advantages

High Purity & Enantiomeric Purity: Our product achieves purity ≥98‑99.5% (chiral HPLC), white to off‑white crystalline powder, molecular weight 428.50 g/mol, MDL MFCD00065557.
Low Impurity Profile: Strict control of D‑enantiomer impurity (≤0.5%), residual solvents, heavy metals (≤10 ppm, ICH Q3D compliant), and moisture (<0.5% by KF titration).
Precise Optical Activity: Specific rotation [α]²⁰ᴰ = −3.5 ± 0.5 ° to −3.5 ± 1 ° (c = 4 in DMF), confirming L‑configuration and preserving the natural arginine stereochemistry.
Batch‑to‑Batch Uniformity: Rigorous analytical testing (chiral HPLC, NMR, LC‑MS, heavy metals by ICP‑MS, residual solvents by GC‑headspace) guarantees consistent quality for cGMP pharmaceutical production.

2. Product Advantages

The Gold‑Standard Arginine Building Block for Boc SPPS: Directly employed as the N‑Boc protected arginine monomer in traditional Boc/Bzl SPPS and in fully automated peptide synthesizers.
Superior Tosyl Side‑Chain Protection: Provides unmatched stability during all coupling steps and ensures clean, quantitative removal during the final HF cleavage — completely avoiding the incomplete deprotection issues that are common with Mtr‑based arginine analogs.
Scalable from R&D to Commercial Production: Validated for research grams (1 g, 5 g, 10 g, 25 g, 50 g, 100 g, 500 g) and bulk industrial scales (1 kg, 5 kg, 10 kg, 25 kg).
Flexible Packaging Options: 5 g, 10 g, 25 g, 50 g, 100 g, 500 g glass bottles (R&D); 1 kg HDPE containers (pilot); 5 kg, 10 kg, 25 kg, 50 kg fiber drums (industrial). Full custom packaging available.
Reliable Supply Chain: Annual capacity in the multi‑ton range, with dedicated cold‑chain warehousing (2‑8 °C, dry, light‑protected) and just‑in‑time delivery capabilities.

3. Application Fields

Pharmaceutical Intermediates: Key building block for GLP‑1 agonists (semaglutide, liraglutide), peptide antibiotics (polymyxin B, colistin), HIV protease inhibitors, renin inhibitors, and custom peptide vaccine manufacturing.
Solid‑Phase Peptide Synthesis (SPPS): Standard arginine building block for manual and automated Boc/Bzl SPPS, reference material for coupling reagent optimization, and protected amino acid unit for stepwise peptide chain assembly.
Antibody‑Drug Conjugate (ADC) and Peptide‑Drug Conjugate (PDC) Development: Essential building block for constructing complex peptide‑based drug delivery systems and bioconjugation processes, enabling enhanced therapeutic selectivity and reduced systemic toxicity.
Diagnostic Reagents: Key reagent in ELISA, lateral flow immunoassays, and rapid point‑of‑care tests requiring arginine‑rich peptide capture probes.
Enzyme Inhibition and Protein‑Protein Interaction Studies: Research tool for investigating arginine‑dependent cellular signaling, enzyme inhibition mechanisms, and transcription factor/DNA‑binding protein activity.

4. Service Support
Our technical team provides full impurity profiling (chiral purity by chiral HPLC, residual solvents by GC‑headspace, heavy metals by ICP‑MS, LC‑MS identity confirmation), custom purification to any desired specification, and complete regulatory documentation (Certificate of Analysis, Technical Data Sheet, Safety Data Sheet, REACH compliance, TSCA certification, DMF support for pharmaceutical customers). We also offer custom synthesis of Boc‑amino acid derivatives, cold‑chain logistics for temperature‑sensitive shipments, and just‑in‑time delivery.

5. Why Choose XinChem

Professionalism: 20 + years in the pharmaceutical intermediate, Boc‑chemistry, and peptide synthesis industries.
Flexibility: Tailored to customer purity specifications, packaging sizes, and regulatory documentation requirements.
Cost‑effectiveness: High purity at competitive industrial pricing.

Post time: May-24-2026

The Gold‑Standard Arginine Building Block for Industrial‑Scale Boc SPPS and Peptide Therapeutics: Boc-Arg(Tos)-OH (CAS 13836-37-8)