The Acid-Labile N-Protected Methionine Building Block for Boc-SPPS, Native Chemical Ligation, and Pharmaceutical Intermediates: BOC-L-Methionine (CAS# 2488-15-5)

BOC-L-Methionine (CAS# 2488-15-5), also known as N-(tert-butoxycarbonyl)-L-methionine, Boc-Met-OH, or N-Boc-L-methionine, is an N-protected methionine derivative with the molecular formula C₁₀H₁₉NO₄S and a molecular weight of 249.33 g/mol. Its molecular structure features an L-methionine backbone with an acid-labile tert-butyloxycarbonyl (Boc) protecting group on the α-amino function and a free carboxylic acid at the C-terminus. The presence of a sulfur-containing thioether side chain distinguishes methionine from other amino acids and confers unique chemical reactivity and biological significance.

As a white to off-white crystalline powder with a melting point of 47–50°C and a specific optical rotation of [α]²⁰/D −22° to −23° (c = 1 in methanol), BOC-L-methionine exhibits good solubility in organic solvents due to its hydrophobic nature. The compound is typically supplied at ≥98% purity (HPLC) and should be stored at 2–8°C.

BOC-L-Methionine is a core building block in Boc-solid-phase peptide synthesis (Boc-SPPS), enabling selective, stepwise elongation of peptide chains with subsequent deprotection under mild acidic conditions (e.g., TFA). The Boc protecting group is particularly valuable where Fmoc chemistry fails—especially for difficult peptide sequences rich in hydrophobic residues that suffer from on-resin aggregation and low coupling efficiency under Fmoc conditions. Beyond peptide synthesis, the compound is classified as a pharmaceutical intermediate and plays essential roles in drug development, biotechnology, recombinant protein production, nutritional research, and analytical chemistry. 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 N-protected amino acid building block.

Core Application Fields and Demand

Market demand for BOC-L-Methionine (CAS# 2488-15-5) is concentrated in three primary sectors: peptide synthesis and native chemical ligation (approximately 50–55% of global consumption), pharmaceutical intermediates and drug development (approximately 25–30%), and biotechnology, nutritional research, and analytical chemistry (approximately 15–20%). Its acid-labile Boc protection, sulfur-containing side chain, and compatibility with Boc-SPPS serve as the core drivers of sustained demand growth.

In peptide synthesis and native chemical ligation, BOC-L-methionine is the premier protected methionine for Boc-SPPS, essential where Fmoc chemistry fails. The compound serves as a protecting group for the amino acid methionine, facilitating the synthesis of peptides in a controlled manner. Difficult peptide sequences rich in hydrophobic residues often fail due to on-resin aggregation and low coupling efficiency under Fmoc chemistry. Boc-Met-OH enables the Boc/Bzl strategy, solving these critical limitations. The compound enables the synthesis of peptide-α-thioesters for native chemical ligation—a powerful methodology for assembling large peptides and proteins that is incompatible with Fmoc chemistry. Through in situ neutralization protocols, Boc-Met-OH provides superior coupling yields for aggregation-prone sequences. Its low racemization profile preserves L-enantiomer stereochemical integrity, ensuring batch-to-batch consistency for regulatory-approved API production. Preferentially used in protein engineering, BOC-L-methionine facilitates investigations into methionine’s role in protein folding and stabilization. The compound is commonly used in peptide synthesis as a protected form of methionine to prevent unwanted side reactions during the synthesis process.

In pharmaceutical intermediate manufacturing, BOC-L-Methionine is classified as a pharmaceutical intermediate. In pharmaceutical research, BOC-L-methionine is used to create modified peptides that can enhance drug efficacy, with its ability to improve the bioavailability of certain compounds being particularly valuable in medicinal chemistry. The compound is utilized in drug development and bioactive molecule synthesis. Amino acids and their derivatives are commercially important as ergogenic supplements and pharmaceutical building blocks.

In biotechnology and recombinant protein production, BOC-L-methionine is essential in the production of recombinant proteins, where it helps in the selective incorporation of methionine in protein structures, ensuring proper folding and functionality. The compound is valuable in peptide-based research and plays a role in investigations into cysteine and methionine’s role in stress physiology and redox homeostasis.

In nutritional research and analytical chemistry, studies on dietary supplements often utilize BOC-L-methionine to explore its role in metabolic processes and its potential benefits for human health, particularly in amino acid supplementation. The compound is employed in various analytical techniques to quantify methionine levels in biological samples, aiding researchers in nutritional studies and metabolic research.

Major Market Participants

The global supply system for BOC-L-Methionine (CAS# 2488-15-5) features a pattern of “specialized peptide synthesis suppliers, multinational chemical distributors, and Chinese manufacturers serving distinct market segments.” As a specialized N-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, biotechnology, and academic research.

In the global research and high-purity segment, key international suppliers include Thermo Fisher Scientific (Acros Organics), offering the compound at ≥98–99% purity; Sigma-Aldrich (Merck), offering 99% purity; Tokyo Chemical Industry (TCI), providing >98.0% (T)(HPLC) purity; Chem-Impex International, offering ≥98% (HPLC) purity; AKSci, offering 95% purity; and BOC Sciences, providing research-grade material. Other suppliers include BenchChem, MuseChem, and Capot Chemical. These suppliers serve the pharmaceutical, biotechnology, and academic research communities with products that meet rigorous quality specifications, typically at 95–99% purity.

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 BOC-L-Methionine from China. Chinese suppliers offer the compound at various purity grades (typically 98% to 99%) and packaging sizes ranging from grams to kilograms, serving both domestic and export markets with competitive pricing. XinChem provides BOC-L-Methionine with stringent quality standards for use in peptide synthesis, pharmaceutical intermediates, and biotechnology applications.

Regional Market Dynamics

The global BOC-L-Methionine 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, peptide synthesis, and academic research industries in these regions.

The Asia-Pacific region has emerged as a significant production hub for BOC-L-Methionine, 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 peptide synthesis industries. Chinese suppliers offer the compound at various purity grades and packaging options, serving both domestic and export markets. The growing pharmaceutical R&D, peptide synthesis, and biotechnology sectors in China, Japan, South Korea, and Southeast Asia continue to drive regional consumption growth.

North America remains a key market for high-purity and research-grade BOC-L-Methionine, driven by demand from the pharmaceutical industry, biotechnology companies, CROs, and academic research institutions. The United States hosts numerous research organizations, pharmaceutical companies, and contract research organizations that require high-quality N-protected amino acid building blocks for drug discovery, peptide synthesis, and medicinal chemistry. Suppliers such as AKSci maintain stock and ship products from the San Francisco Bay Area, California. Thermo Fisher Scientific 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 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 chiral building blocks with comprehensive documentation. The compound has been imported in bulk form from Italy as a pharmaceutical intermediate. TCI and other distributors serve the European market with in-stock availability.

Japan represents a specialized market where BOC-L-Methionine is supplied by Tokyo Chemical Industry (TCI) and other distributors for pharmaceutical research, peptide synthesis, and fine chemical applications.

Regulatory and Safety Considerations

As a research chemical, pharmaceutical intermediate, and peptide synthesis building block, BOC-L-Methionine (CAS# 2488-15-5) is subject to regulatory oversight in major global economies. Compliance with relevant regulations is essential for market access and trade.

GHS classification and handling: BOC-L-Methionine 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). The compound carries risk code Xn (Harmful) with R20/21/22-36/37/38 (harmful by inhalation, in contact with skin, and if swallowed; irritates eyes, respiratory system, and skin). Precautionary measures include wearing protective gloves, eye protection, face protection, and N95 mask; storing at 2–8°C; and maintaining good ventilation. The WGK Germany classification is 3 (high hazard to water). Personal protective equipment including lab gloves, safety glasses, or face shields should be worn during handling.

Transport information: BOC-L-Methionine is not classified as hazardous material for DOT/IATA transport purposes. Proper packaging, labeling, and documentation are nevertheless required for international shipping in compliance with the International Maritime Dangerous Goods Code (IMDG Code) and other transport regulations. The compound is not DEA-regulated and is not an antibiotic.

Regulatory compliance: In the European Union, the compound must comply with REACH registration requirements and CLP classification under Regulation (EC) No 1272/2008 for import and use. Manufacturers and suppliers must provide comprehensive Safety Data Sheets (SDS) and maintain appropriate documentation. In the United States, BOC-L-Methionine 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. The compound has an EINECS number of 219-639-3 and an MDL number of MFCD00065586.

Future Outlook

The market outlook for BOC-L-Methionine is positive, supported by several key growth drivers across its major application segments. While the compound remains a relatively specialized N-protected amino acid building block, its essential role in Boc-SPPS, native chemical ligation, and pharmaceutical intermediate manufacturing positions it for steady growth in the coming years. The broader methionine market was valued at approximately USD 4.83 billion in 2025 and is projected to reach USD 8.05 billion by 2034, growing at a CAGR of 5.8%, with the protected amino acid derivatives segment benefiting from this growth.

Key growth drivers include:

1. Expansion of the peptide therapeutics market: The rapidly growing global market for peptide drugs—projected to exceed USD 50 billion by 2030—drives demand for high-quality N-protected amino acid building blocks, including BOC-L-Methionine, for both research and commercial peptide manufacturing.
2. Growth in Boc-SPPS and native chemical ligation: Increasing adoption of Boc-SPPS for difficult peptide sequences and native chemical ligation for assembling large peptides and proteins drives demand for Boc-protected amino acids, particularly for sequences where Fmoc chemistry fails due to aggregation.
3. Expansion of pharmaceutical R&D and API manufacturing: Increasing investment in drug discovery and development, particularly in peptide-based therapeutics and bioactive molecules, supports demand for high-quality pharmaceutical intermediates.
4. Growth in biotechnology and recombinant protein production: The expanding biopharmaceutical industry and increasing production of recombinant proteins drive demand for protected amino acids for selective incorporation into protein structures.
5. Increasing focus on sulfur-containing amino acid research: Growing interest in methionine’s role in protein folding, stabilization, stress physiology, and redox homeostasis supports demand for BOC-L-methionine in protein engineering and biochemical research.

Challenges and considerations:

• Regulatory compliance: Increasingly stringent pharmaceutical and chemical regulations may require ongoing investment in quality systems and documentation.
• Competition from alternative protecting groups: The market faces competition from Fmoc-protected amino acid derivatives for certain peptide synthesis applications.
• Limited scale: As a relatively specialized compound, the market for BOC-L-Methionine is smaller than that of commodity amino acids.
• Storage requirements: The compound requires storage at 2–8°C, which may increase handling and logistics costs.

To succeed in this evolving market landscape, suppliers must focus on product quality (particularly enantiomeric purity, chemical 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) confirming enantiomeric purity, flexible packaging options, and technical support for peptide synthesis and pharmaceutical applications will be well-positioned to capture growing demand.

Shanghai XinChem Co., Ltd. (XinChem)

As a world-leading supplier of organic chemicals and N-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 BOC-L-Methionine (CAS# 2488-15-5) 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 acid-labile N-protected methionine 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 BOC-L-Methionine products. The production process incorporates established synthetic routes—including the protection of L-methionine using di-tert-butyl dicarbonate (Boc₂O) in the presence of a base such as triethylamine—enabling the delivery of products with purity ≥98% (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 Boc-SPPS, native chemical ligation, pharmaceutical intermediate synthesis, and biotechnology applications.

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), specific optical rotation [α]²⁰/D −22° to −23° (c = 1 in methanol), melting point (47–50°C), and impurity profiles. This commitment to quality ensures that XinChem’s BOC-L-Methionine meets the stringent requirements of pharmaceutical R&D, peptide synthesis, and biotechnology applications.

2. Product Advantages

High Purity and Consistent Quality
XinChem offers BOC-L-Methionine with purity ≥98% (HPLC), ensuring optimal performance in Boc-SPPS, native chemical ligation, pharmaceutical intermediate synthesis, and biotechnology applications. The product’s high purity minimizes the risk of unwanted side reactions and impurities, making it suitable for demanding applications in drug discovery, peptide therapeutics, and fine chemical synthesis.

Comprehensive Specifications
Key specifications include:

• Molecular Formula: C₁₀H₁₉NO₄S
• Molecular Weight: 249.33 g/mol
• CAS Number: 2488-15-5
• EINECS Number: 219-639-3
• MDL Number: MFCD00065586
• Synonyms: Boc-Met-OH, N-Boc-L-methionine, N-(tert-Butoxycarbonyl)-L-methionine
• Appearance: White to off-white crystalline powder
• Purity: ≥98% (HPLC)
• Specific Optical Rotation: [α]²⁰/D −22° to −23° (c = 1 in methanol)
• Melting Point: 47–50°C
• Storage: 2–8°C, sealed in dry conditions
• Solubility: Soluble in organic solvents; hydrophobic nature enhances compatibility with organic solvents

Flexible Packaging Solutions
XinChem provides a range of packaging options to accommodate diverse customer needs, from laboratory-scale quantities (grams) to industrial-scale packaging (kilograms) and bulk shipments. Customized packaging solutions are available upon request, ensuring safe handling, storage, and transportation.

3. Application Fields

As a versatile acid-labile N-protected methionine building block, BOC-L-Methionine (CAS# 2488-15-5) exhibits wide application value across multiple industries:

Peptide Synthesis and Native Chemical Ligation:

• Core building block for Boc-solid-phase peptide synthesis (Boc-SPPS)
• Enables synthesis of peptide-α-thioesters for native chemical ligation, incompatible with Fmoc chemistry
• Superior coupling yields for aggregation-prone sequences via in situ neutralization protocols
• Low racemization profile preserves L-enantiomer stereochemical integrity
• Protecting group for methionine in controlled peptide synthesis
• Protein engineering investigations into methionine’s role in protein folding and stabilization

Pharmaceutical Intermediates and Drug Development:

• Pharmaceutical intermediate for API manufacturing
• Creation of modified peptides to enhance drug efficacy
• Bioavailability improvement in medicinal chemistry
• Bioactive molecule synthesis

Biotechnology and Recombinant Protein Production:

• Selective incorporation of methionine in protein structures
• Proper protein folding and functionality
• Research into cysteine and methionine’s role in stress physiology and redox homeostasis

Nutritional Research:

• Studies on dietary supplements and metabolic processes
• Amino acid supplementation research

Analytical Chemistry:

• Quantification of methionine levels in biological samples
• Nutritional studies and metabolic research

4. Service Support

Technical Expertise and Customized Solutions
XinChem’s team of experienced chemists and pharmaceutical scientists provides full technical support throughout the customer journey—from product selection and specification development to application guidance and troubleshooting. Whether customers require optimization of Boc-SPPS protocols, guidance on native chemical ligation strategies, deprotection conditions, 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) 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 N-protected amino acid synthesis and supply.
• Quality: Rigorous quality control, high purity (≥98%), 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 including COA confirming enantiomeric purity.

Contact us today to start your partnership with XinChem!

Website: www.xinchem.com

Email: sales1@xinchem.com

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