Boc-His(Tos)-OH

Boc-His(Tos)-OH is a specialized building block for Boc-strategy solid-phase peptide synthesis, serving as the standard reagent for introducing L-histidine residues with complete protection of the reactive imidazole side chain. The tosyl protecting group on the imidazole nitrogen ensures that Boc-His(Tos)-OH can be coupled without the side reactions — such as acylation at the imidazole nitrogen or racemization — that often plague unprotected or inadequately protected histidine derivatives. In peptide drug discovery, Boc-His(Tos)-OH is employed in the synthesis of bioactive peptides where histidine plays a critical role in metal binding, enzymatic catalysis, or pH-dependent conformational changes. The compound is also essential for constructing peptide-based enzyme inhibitors, antimicrobial peptides, and histidine-rich metal-chelating peptides. The crystalline solid form and high purity (≥98.0% TLC) of Boc-His(Tos)-OH make it easy to handle and integrate into standard SPPS workflows, while the well-characterized optical activity ([α]²⁰/D = +16±1°, c=1% in methanol) ensures enantiopure histidine incorporation.

 

Product Parameters

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Parameter	Specification
Product Name	Boc-His(Tos)-OH
CAS Number	35899-43-5
Molecular Formula	C₁₈H₂₃N₃O₆S
Molecular Weight	409.46 g/mol
Appearance	White to almost white crystalline powder
Melting Point	~125 °C (dec.)
Optical Rotation	[α]²⁰/D = +16±1° (c=1% in methanol)
Density	1.19 g/cm³
Storage Condition	Store at 4 °C; sealed, cool, dry, and ventilated
pKa	3.50±0.10
Storage Condition	-20℃

 

Product Advantages

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Complete Imidazole Protection with Tosyl Group

Boc-His(Tos)-OH features the tosyl (p-toluenesulfonyl) protecting group on the imidazole nitrogen, which effectively masks the nucleophilic and basic character of the histidine side chain. This prevents acylation at the imidazole nitrogen, racemization, and other side reactions during peptide chain elongation.

 

Orthogonal Deprotection Strategy

The Boc and tosyl protecting groups in Boc-His(Tos)-OH can be removed under different conditions: the Boc group is cleaved by mild acid (TFA), while the tosyl group requires stronger acid conditions (HF or TFMSA). This orthogonal deprotection strategy enables selective unmasking during peptide synthesis.

 

High Purity with Full Characterization

Boc-His(Tos)-OH is supplied with TLC purity ≥98.0%, optical rotation [α]²⁰/D = +16±1° (c=1% in methanol), and moisture content ≤0.5%. The white to pale yellow crystalline powder form ensures accurate weighing and easy handling.

 

Essential for Histidine-Containing Bioactive Peptides

Histidine plays critical roles in enzyme catalysis, metal ion coordination, and pH-dependent proton transfer. Boc-His(Tos)-OH is essential for synthesizing histidine-containing bioactive peptides, including enzyme inhibitors, antimicrobial peptides, and metal-chelating peptides.

 

Stable Crystalline Solid for Reliable Handling

Boc-His(Tos)-OH is supplied as a stable crystalline solid with melting point ~125 °C (dec.). The crystalline form ensures long-term stability under recommended storage conditions (4 °C, sealed, dry).

 

Product Quality Assurance

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Cosperpharm has established a comprehensive quality assurance system for Boc-His(Tos)-OH that meets the rigorous expectations of peptide synthesis intermediates and research reagents:

 

Thorough analytical characterization. Each batch undergoes multi-technique analytical release testing: TLC purity (≥98.0%), optical rotation verification ([α]²⁰/D = +16±1° in methanol), moisture content determination (≤0.5%), melting point verification (~125 °C, dec.), appearance verification (white to pale yellow crystalline powder), and identity confirmation by appropriate analytical methods.

 

Full batch traceability with retention samples. From raw material procurement through synthesis, purification, and final packaging, every step is fully documented and traceable. Each batch receives a unique lot number with sufficient retention samples maintained in accordance with Cosperpharm quality procedures.

 

Stability monitoring program. Cosperpharm conducts ongoing stability studies under recommended storage conditions (4 °C, sealed, dry). Stability summaries are updated regularly, with full data packages available to support customer research and regulatory submissions.

 

Documentation ready for research and regulatory use. Every shipment includes a Certificate of Analysis (COA) with batch-specific purity and characterization data, a Material Safety Data Sheet (SDS), and customs documentation for international delivery. For customers developing peptide therapeutics, Cosperpharm provides DMF-ready documentation packages, method validation reports, stability data, and custom quality agreements upon request.

 

Customer-initiated quality audits. Qualified customers are welcome to audit Cosperpharm's manufacturing, quality control, and documentation facilities. Please contact our regulatory team to schedule an audit.

 

Storage Conditions

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Store Boc-His(Tos)-OH in a tightly sealed container in a dry, cool, well-ventilated area at -20°C. Protect from moisture and light. The compound is stable under recommended storage conditions.

 

Shelf life: Please refer to the Certificate of Analysis for batch-specific expiration dating. Under recommended storage conditions, Boc-His(Tos)-OH typically maintains ≥98% purity for 2–3 years.

 

Handling precautions: Use in a fume hood. Wear chemical-resistant gloves, safety goggles, and a lab coat. Avoid generating dust or aerosols. Do not eat, drink, or smoke in work areas. After handling, wash hands thoroughly. Refer to the Safety Data Sheet (SDS) for complete safety information.

 

Contact Us

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Histidine incorporation in peptide synthesis presents unique challenges — and Boc-His(Tos)-OH from Cosperpharm provides the solution. Whether you are synthesizing enzyme inhibitors, antimicrobial peptides, or metal-chelating therapeutic candidates, our team is ready to support your success with high-quality product, comprehensive documentation, and expert technical guidance. Contact us today.