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N-Cbz-O-tert-butyl-L-serine (CAS# 1676-75-1), also known as Z-Ser(tBu)-OH, N-Carbobenzoxy-O-tert-butyl-L-serine, or N-Benzyloxycarbonyl-O-tert-butyl-L-serine, is an orthogonally protected L-serine derivative with the molecular formula C₁₅H₂₁NO₅ and a molecular weight of 295.33–295.34 g/mol. Its molecular structure features an L-serine backbone bearing a benzyloxycarbonyl (Cbz/Z) protecting group on the α-amino functionality and a tert-butyl (tBu) ether protecting group on the side-chain hydroxyl. This dual-protection architecture—combining a hydrogenolysis-labile N-Cbz group with an acidolysis-labile O-tBu group—confers exceptional chemoselectivity for sequential, orthogonal deprotection in convergent peptide synthesis strategies.

As a white crystalline powder with a melting point of 86°C (literature 148°C for the alternate polymorph) and an optical rotation of 20° (c=2, EtOH), the compound is soluble in common organic solvents and should be stored at 2–8°C (long-term at -20°C) in a tightly sealed container protected from moisture. It is supplied at ≥98% purity (HPLC) with ≥99.5% (Chiral HPLC) grades available for demanding applications.

N-Cbz-O-tert-butyl-L-serine is the definitive protected serine building block for solution-phase and solid-phase peptide synthesis (SPPS), enabling the selective incorporation of serine residues without unwanted side-chain reactions during chain elongation. Its unique orthogonal protection strategy—eliminating uncontrolled side-chain reactivity that would otherwise derail sequence-specific peptide assembly—makes it indispensable in peptide-based drug development, protein engineering, and the synthesis of enzyme inhibitors and receptor agonists. Based on its chemical characteristics and industrial significance, this article systematically analyzes the key properties, core application areas, global market structure, regulatory landscape, and future outlook of this strategically important protected amino acid building block.

Key Properties and Reactivity Profile

N-Cbz-O-tert-butyl-L-serine (CAS# 1676-75-1) is an orthogonally protected serine derivative whose value derives from the chemoselective deprotection capability of its two protecting groups.

Key physicochemical parameters include:

Molecular Formula: C₁₅H₂₁NO₅
Molecular Weight: 295.33–295.34 g/mol
CAS Number: 1676-75-1
EINECS Number: 216-827-7
MDL Number: MFCD00038275
Synonyms: Z-Ser(tBu)-OH; N-Carbobenzoxy-O-tert-butyl-L-serine; N-Benzyloxycarbonyl-O-tert-butyl-L-serine; (S)-2-(((Benzyloxy)carbonyl)amino)-3-(tert-butoxy)propanoic acid
IUPAC Name: (2S)-3-[(2-methylpropan-2-yl)oxy]-2-(phenylmethoxycarbonylamino)propanoic acid
Appearance: White crystalline powder
Purity: ≥98% (HPLC); ≥99.5% (Chiral HPLC) available
Melting Point: 86°C (literature 148°C for alternate polymorph)
Boiling Point: 465.3±45.0°C at 760 mmHg
Density: 1.174±0.060 g/cm³
Flash Point: 235.2°C
Optical Rotation: 20° (c=2, EtOH)
Solubility: Soluble in common organic solvents
Storage: 2–8°C (long-term at -20°C), protected from moisture
SMILES: CC(C)(C)OCC@HC(=O)O
InChIKey: TXDGEONUWGOCJG-LBPRGKRZSA-N
GHS Classification: Warning; H302 (Harmful if swallowed), H315 (Causes skin irritation), H319 (Causes serious eye irritation), H335 (May cause respiratory irritation)
WGK Germany: 3 (high hazard to water)
HS Code: 29242990

The compound’s reactivity is defined by its two orthogonal protecting groups. The N-Cbz group is selectively removed under hydrogenolysis conditions (H₂/Pd-C) or strong acids (HBr/AcOH), while the O-tBu ether is cleaved under acidic conditions (TFA, HCl). This orthogonal strategy enables sequential, chemoselective deprotection in convergent peptide synthesis—unprotected serine would cause uncontrolled side-chain reactivity, derailing sequence-specific peptide assembly. The carboxylic acid at the C-terminus enables standard peptide coupling after appropriate activation, and the stereodefined L-configuration ensures correct stereochemical outcomes in peptide chain elongation.

Core Application Fields and Demand

Market demand for N-Cbz-O-tert-butyl-L-serine (CAS# 1676-75-1) is concentrated in three primary sectors: peptide synthesis and peptide-based drug development (approximately 55–60% of global consumption), pharmaceutical intermediates and API manufacturing (approximately 20–25%), and protein engineering, chemical biology, and research applications (approximately 15–20%). Its orthogonal protection strategy and role as the definitive protected serine building block serve as the core drivers of sustained demand growth.

In peptide synthesis and peptide-based drug development, N-Cbz-O-tert-butyl-L-serine is a crucial protected amino acid for both solid-phase and solution-phase peptide synthesis. The compound is used as a building block for incorporating serine residues into peptides and proteins, enabling the development of peptide-based therapeutics including enzyme inhibitors, receptor agonists, and synthetic peptides for research and industrial applications. It is compatible with standard amide bond formation strategies after appropriate activation and deprotection. The compound has been successfully employed in the synthesis of thrombin inhibitors, where Z-Ser(tBu)-OH was coupled with H-Pro-OCH₃·HCl to give the dipeptide Z-Ser(tBu)-Pro-OCH₃, a key intermediate in anticoagulant drug development. It is also used in the synthesis of peptide prodrugs, where the Cbz and tBu protection strategy enables precise control over the site-specific incorporation of serine residues.

In pharmaceutical intermediates and API manufacturing, N-Cbz-O-tert-butyl-L-serine serves as an intermediate in the synthesis of active pharmaceutical ingredients (APIs) and bioactive compounds. It can be used to synthesize antibiotics, drugs, and other organic compounds. The compound’s stereodefined chiral amino acid framework with an esterified carboxyl group is suitable for peptide coupling chemistry, making it valuable in the synthesis of complex drug molecules.

In protein engineering and chemical biology, N-Cbz-O-tert-butyl-L-serine supports research in protein engineering by enabling precise modifications at intended serine residues. The compound is used for the incorporation of serine residues with specific protections to facilitate precise and controlled synthesis. It also finds application in the development of peptide-based probes and chemical biology tools for studying enzyme mechanisms and protein-protein interactions.

Major Market Participants

The global supply system for N-Cbz-O-tert-butyl-L-serine (CAS# 1676-75-1) features a pattern of “specialized protected amino acid manufacturers, multinational research chemical distributors, and Chinese producers serving distinct market segments.” As a specialized protected amino acid building block rather than a bulk commodity, the market is characterized by a moderate number of suppliers catering to pharmaceutical R&D, peptide synthesis, and academic research.

In the global research and high-purity segment, key international suppliers include Tokyo Chemical Industry (TCI), offering the compound at ≥98.0% purity (T) under product number C1381, with pricing of $22.00 for 1 g and $70.00 for 5 g. AKSci offers the compound at 98% (HPLC) purity under product code E215, with stock shipped from the SF Bay Area, California. Fluorochem (UK) offers the compound under product code M03055 with pricing from £5.00/1 g to £234.00/500 g, with stock availability in the UK, Europe, and China. BOC Sciences offers the compound at ≥99.5% purity (Chiral HPLC) under catalog number BAT-003411, with capabilities including custom amino acid synthesis, stable isotope-labeled amino acids, and scalable production from grams to kilograms. Sigma-Aldrich (Merck) offers the compound at ≥98.0% purity (TLC) with reaction suitability for solution-phase and Boc solid-phase peptide synthesis. Other suppliers include Matrix Scientific and CymitQuimica.

In the industrial and large-scale production segment, Chinese manufacturers have emerged as significant players in the global supply chain. XinChem is a reliable manufacturer and supplier of high-purity N-Cbz-O-tert-butyl-L-serine from China, offering the compound with stringent quality standards for use in peptide synthesis, pharmaceutical intermediate manufacturing, and protein engineering research. XinChem provides the compound as a white crystalline powder with comprehensive quality documentation and flexible packaging options. Other Chinese suppliers include Sichuan Tongsheng Biopharmaceutical (四川同晟生物医药), a specialized manufacturer offering custom services with pricing of approximately ¥1,111/kg, GL Biochem (Shanghai) (吉尔生化), offering the compound at approximately ¥4,000/kg, Capot Chemical, offering 98% minimum purity with moisture ≤0.5%, and Bide Pharmatech (毕得医药), offering the compound at 97% purity with batch quality inspection reports (NMR, HPLC, GC). Chinese suppliers offer the compound at various purity grades (typically 97–99%) and packaging options—from grams to multi-kilogram quantities—serving both domestic and export markets with competitive pricing.

Regional Market Dynamics

The global N-Cbz-O-tert-butyl-L-serine market exhibits distinct regional characteristics, with production concentrated in Asia-Pacific (particularly China) and consumption distributed across North America, Europe, and the Asia-Pacific region, aligned with the pharmaceutical, biotechnology, and peptide synthesis industries in these regions.

The Asia-Pacific region has emerged as a significant production hub for N-Cbz-O-tert-butyl-L-serine, with China hosting numerous manufacturers and suppliers including XinChem. The region’s competitive advantages include lower production costs, established chemical infrastructure, and proximity to rapidly growing pharmaceutical and biotechnology industries. Chinese suppliers offer the compound at various purity grades (typically 97–99%) and packaging options, serving both domestic and export markets. The growing pharmaceutical R&D, peptide therapeutics, and API manufacturing sectors in China, Japan, South Korea, and India continue to drive regional consumption growth. TCI Chemicals maintains inventory in Japan and China, with the ability to ship from regional warehouses.

North America remains a key market for high-purity and research-grade N-Cbz-O-tert-butyl-L-serine, driven by demand from the pharmaceutical industry, biotechnology companies, and academic research institutions. The United States hosts numerous research organizations, pharmaceutical companies, and contract research organizations that require high-quality protected amino acid building blocks for peptide drug discovery and development. AKSci maintains stock and ships from the SF Bay Area, California, while BOC Sciences and Sigma-Aldrich serve the North American market with extensive distribution networks. The region’s well-established regulatory framework and emphasis on product quality support demand for high-grade research chemicals and pharmaceutical intermediates.

Europe is characterized by stringent regulatory requirements, including REACH registration, and a strong focus on quality and sustainability in pharmaceutical and chemical research. European pharmaceutical companies, peptide synthesis laboratories, and research institutions demand high-purity protected amino acid building blocks with comprehensive documentation. Fluorochem (UK) and Sigma-Aldrich serve the European market with in-stock availability and established distribution networks.

Japan represents a specialized market where N-Cbz-O-tert-butyl-L-serine is supplied by TCI Chemicals and other distributors for pharmaceutical research, peptide synthesis, and fine chemical applications.

Regulatory and Safety Considerations

As a research chemical, peptide synthesis building block, and pharmaceutical intermediate, N-Cbz-O-tert-butyl-L-serine (CAS# 1676-75-1) is subject to regulatory oversight in major global economies. Compliance with relevant regulations is essential for market access and trade.

GHS classification and handling: N-Cbz-O-tert-butyl-L-serine is classified with the signal word ”Warning” . Hazard statements include H302 (Harmful if swallowed), H315 (Causes skin irritation), H319 (Causes serious eye irritation), and H335 (May cause respiratory irritation). Precautionary statements include P260 (Do not breathe dust/fume/gas/mist/vapours/spray), P264 (Wash hands thoroughly after handling), P270 (Do not eat, drink or smoke when using this product), P271 (Use only outdoors or in a well-ventilated area), P280 (Wear protective gloves/protective clothing and eye/face protection), P301+P310 (IF SWALLOWED: Immediately call a POISON CENTER/doctor), P301+P330+P331 (IF SWALLOWED: Rinse mouth. Do NOT induce vomiting), P303+P361+P353 (IF ON SKIN: Take off immediately all contaminated clothing; rinse skin with water), and P304+P340 (IF INHALED: Remove person to fresh air and keep comfortable for breathing). The compound is classified as Acute Tox. 4 Oral, Skin Irrit. 2, Eye Irrit. 2, and STOT SE 3. The WGK Germany classification is 3 (high hazard to water).

Storage and stability: N-Cbz-O-tert-butyl-L-serine should be stored at 2–8°C for short-term storage or at -20°C for long-term storage (3 years at -20°C, 2 years at 4°C). The compound is stable under recommended storage conditions but should be kept in a tightly sealed container protected from moisture. When preparing solutions, it is recommended to use them fresh for each application; if short-term storage is necessary (up to 24 hours), solutions should be kept at low temperature.

Regulatory compliance: In the European Union, the compound must comply with REACH registration requirements for import and use. The compound has an EINECS number of 216-827-7. Manufacturers and suppliers must provide comprehensive Safety Data Sheets (SDS) and maintain appropriate documentation. In the United States, N-Cbz-O-tert-butyl-L-serine is intended for research and development use only and is not intended for therapeutic, food, cosmetic, or consumer applications unless explicitly stated otherwise. For pharmaceutical intermediate applications, manufacturers must comply with relevant FDA regulations and quality standards.

Transport information: N-Cbz-O-tert-butyl-L-serine is not classified as hazardous material for DOT/IATA transport purposes. Proper packaging, labeling, and documentation are nevertheless required for international shipping. The HS code for the compound is 29242990 (China export).

Future Outlook

The market outlook for N-Cbz-O-tert-butyl-L-serine is positive, supported by several key growth drivers across its major application segments. While the compound remains a relatively specialized protected amino acid building block, its essential role in peptide synthesis and protein engineering positions it for steady growth in the coming years.

Key growth drivers include:

Expansion of the peptide therapeutics market: The rapidly growing global market for peptide drugs—including GLP-1 receptor agonists, peptide antibiotics, and peptide-drug conjugates—drives demand for high-quality protected amino acid building blocks, including N-Cbz-O-tert-butyl-L-serine, for both research and commercial peptide manufacturing.
Growth in peptide-based drug development: The compound’s role as a building block for enzyme inhibitors and receptor agonists supports the expanding pipeline of peptide-based therapeutics, particularly in oncology, metabolic diseases, and CNS disorders.
Expansion of protein engineering and chemical biology research: The growing emphasis on precise modifications at serine residues for protein engineering and chemical biology applications drives demand for orthogonally protected serine derivatives.
Increasing demand for solution-phase peptide synthesis: The compound’s compatibility with solution-phase peptide synthesis and Boc solid-phase peptide synthesis protocols supports its use in convergent peptide synthesis strategies.
Growth in pharmaceutical R&D in Asia: The increasing investment in peptide drug discovery and API manufacturing in China and India supports demand for high-quality protected amino acid building blocks.

Challenges and considerations:

Regulatory compliance: Increasingly stringent pharmaceutical and chemical regulations may require ongoing investment in quality systems and documentation.
Storage requirements: The compound requires storage at 2–8°C or -20°C, which may increase handling and logistics costs.
Competition from alternative protecting groups: The market faces competition from Fmoc-protected serine derivatives for certain peptide synthesis applications.
Limited scale: As a relatively specialized compound, the market for N-Cbz-O-tert-butyl-L-serine is smaller than that of commodity amino acids.
Handling requirements: The compound’s irritant classification (H302, H315, H319, H335) requires appropriate safety measures during handling and storage.

To succeed in this evolving market landscape, suppliers must focus on product quality (particularly enantiomeric purity and batch-to-batch consistency), supply chain reliability, regulatory compliance, and responsive customer service. Companies that can offer high-purity products with comprehensive Certificates of Analysis (COA) documenting enantiomeric purity, flexible packaging options, and technical support for peptide synthesis, pharmaceutical, and protein engineering applications will be well-positioned to capture growing demand.

Shanghai XinChem Co., Ltd. (XinChem)

As a world-leading supplier of organic chemicals and protected amino acid building blocks, Shanghai XinChem Co., Ltd. (XinChem) is dedicated to meeting the innovative needs of the pharmaceutical, biotechnology, peptide synthesis, and fine chemical industries. Leveraging extensive experience and advanced manufacturing capabilities, XinChem provides high-quality N-Cbz-O-tert-butyl-L-serine (CAS# 1676-75-1) to customers worldwide. As a trusted manufacturer and supplier based in China, XinChem combines competitive pricing, reliable supply, and exceptional service to establish itself as a preferred partner for research institutions, pharmaceutical companies, peptide synthesis laboratories, and biotechnology companies seeking this versatile orthogonally protected serine building block.

1. Technical Advantages

Advanced Synthesis and Purification Processes
XinChem utilizes state-of-the-art manufacturing facilities and rigorous quality control measures to ensure the purity, consistency, and safety of its N-Cbz-O-tert-butyl-L-serine products. The production process incorporates established synthetic routes—including the reaction of tert-butyl L-serine with benzyl chloroformate under basic conditions to introduce the Cbz protecting group—enabling the delivery of products with purity ≥98% (HPLC) and ≥99.5% (Chiral HPLC) to meet diverse application requirements. Strict process control ensures consistent enantiomeric purity (L-configuration), minimal impurities, and batch-to-batch reproducibility, providing customers with reliable performance in peptide synthesis, pharmaceutical intermediate manufacturing, and protein engineering.

Full-Chain Quality Control
The production process strictly adheres to international quality standards, with comprehensive quality control covering raw material sourcing, in-process monitoring, and finished product testing. Each batch is accompanied by a detailed Certificate of Analysis (COA) documenting physical and chemical properties, purity data (HPLC and Chiral HPLC), melting point, optical rotation, and impurity profiles. This commitment to quality ensures that XinChem’s N-Cbz-O-tert-butyl-L-serine meets the stringent requirements of peptide synthesis, pharmaceutical R&D, and research applications.

2. Product Advantages

High Purity and Consistent Quality
XinChem offers N-Cbz-O-tert-butyl-L-serine with purity ≥98% (HPLC) and ≥99.5% (Chiral HPLC) available, ensuring optimal performance in peptide synthesis, pharmaceutical intermediate manufacturing, and protein engineering. The product’s high purity and consistent enantiomeric configuration minimize the risk of unwanted side reactions and impurities, making it suitable for demanding applications in peptide drug development and chemical biology research.

Comprehensive Specifications
Key specifications include:

Molecular Formula: C₁₅H₂₁NO₅
Molecular Weight: 295.33–295.34 g/mol
CAS Number: 1676-75-1
Synonyms: Z-Ser(tBu)-OH; N-Carbobenzoxy-O-tert-butyl-L-serine; N-Benzyloxycarbonyl-O-tert-butyl-L-serine
MDL Number: MFCD00038275
EINECS Number: 216-827-7
Appearance: White crystalline powder
Purity: ≥98% (HPLC) / ≥99.5% (Chiral HPLC) available
Melting Point: 86°C
Optical Rotation: 20° (c=2, EtOH)
Storage: 2–8°C (long-term at -20°C), protected from moisture
GHS Classification: Warning; H302, H315, H319, H335

Flexible Packaging Solutions
XinChem provides a range of packaging options to accommodate diverse customer needs, from laboratory-scale quantities (100 mg, 250 mg, 500 mg, 1 g, 5 g) to industrial-scale packaging (10 g, 25 g, 100 g, 500 g, 1 kg) and bulk shipments. Customized packaging solutions are available upon request, ensuring safe handling, storage, and transportation with appropriate protection from moisture.

3. Application Fields

As a versatile orthogonally protected serine building block, N-Cbz-O-tert-butyl-L-serine (CAS# 1676-75-1) exhibits wide application value across multiple industries:

Peptide Synthesis:

Protected building block for solid-phase and solution-phase peptide synthesis
Compatible with standard amide bond formation strategies after activation and deprotection
Building block for enzyme inhibitors (e.g., thrombin inhibitors) and receptor agonists
Precursor for peptide prodrugs with site-specific serine incorporation
Use in convergent peptide synthesis strategies with orthogonal deprotection

Pharmaceutical Intermediates:

Intermediate for the synthesis of APIs and bioactive compounds
Precursor for antibiotics, drugs, and other organic compounds
Building block for pharmaceutical research and development

Protein Engineering and Chemical Biology:

Tool for precise modifications at intended serine residues
Reagent for studying enzyme mechanisms and protein-protein interactions
Building block for peptide-based probes and chemical biology tools

4. Service Support

Technical Expertise and Customized Solutions
XinChem’s team of experienced chemists and application engineers provides full technical support throughout the customer journey—from product selection and specification development to application guidance and troubleshooting. Whether customers require optimization of peptide coupling conditions, guidance on orthogonal deprotection strategies, or assistance with regulatory documentation, XinChem’s technical experts are ready to help. Custom synthesis and contract manufacturing with flexible scaling from R&D to commercial quantities are available upon request.

Global Logistics and Reliable Supply
With established supply chains serving markets across Europe, North America, Asia-Pacific, and beyond, XinChem ensures timely delivery and consistent product availability. The company’s logistics team manages all aspects of international shipping, including customs clearance and documentation, with appropriate temperature control (2–8°C) and moisture protection for product stability.

Regulatory Support
XinChem provides comprehensive documentation to support regulatory compliance, including Safety Data Sheets (SDS), Certificates of Analysis (COA), and other required certificates. The company stays current with evolving regulatory requirements in major markets, including REACH, TSCA, and other regional regulations, helping customers navigate the complexities of global trade.

5. Reasons to Choose XinChem

Professionalism: Extensive experience and deep expertise in protected amino acid synthesis and supply.
Quality: Rigorous quality control, high purity (≥98% to ≥99.5%), and adherence to international standards.
Reliability: Stable supply, competitive pricing, and timely delivery.
Flexibility: Customized solutions to meet diverse customer needs, including custom synthesis and packaging.
Service: Responsive technical support and comprehensive documentation.

Website: www.xinchem.com

Email: sales1@xinchem.com

WhatsApp: +86 18049800532

Post time: Sep-20-2026

The Orthogonally Protected Serine Building Block for Peptide Synthesis, Protein Engineering, and Pharmaceutical Intermediates: N-Cbz-O-tert-butyl-L-serine (Z-Ser(tBu)-OH, CAS# 1676-75-1)