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Fmoc-D-Lys(Boc)-OH (Nα-fluorenylmethoxycarbonyl-Nε-tert-butyloxycarbonyl-D-lysine, CAS: 92122-45-7) is an orthogonally protected D-lysine derivative with the molecular formula C₂₆H₃₂N₂O₆ and a molecular weight of 468.54 g/mol. Its structure features the Fmoc (9‑fluorenylmethoxycarbonyl) group, which is quantitatively removed by mild secondary amine base (piperidine) during SPPS cycles, and the Boc (tert‑butyloxycarbonyl) group which is cleaved by moderately strong acid (TFA). This orthogonal protection strategy — combined with the enantiomeric purity of the rare, non-natural D‑lysine stereochemistry — makes Fmoc-D-Lys(Boc)-OH the standard N‑Fmoc building block for introducing D‑lysine residues into peptide chains.

The D‑enantiomer of lysine is a critical component in peptide drugs designed for high metabolic stability. Peptidic drugs containing D‑amino acids exhibit dramatically extended plasma half‑lives, resistance to proteolytic degradation by trypsin, chymotrypsin and other endopeptidases, and preserved or enhanced biological activity. The ε‑Boc side‑chain protection prevents aggregation and side reactions during chain elongation, while the ε‑NH₂ free base, liberated after global deprotection, serves as an orthogonal chemical handle for bioconjugation. This dual protection meets the rigorous demands of fully automated SPPS, solid‑phase and solution‑phase custom peptide manufacturing, and industrial-scale peptide API production.

From a synthetic perspective, Fmoc-D-Lys(Boc)-OH can be coupled using standard Fmoc SPPS coupling reagents (HATU, HBTU, PyBOP, COMU, DIC/Oxyma, DIC/HOBt) with yields routinely ≥98%. The compound can be used to synthesise chains of up to 17 amino acid residues in length.

Core Application Fields and Market Demand

Market demand for Fmoc-D-Lys(Boc)-OH is strongly concentrated in four major sectors: Peptide therapeutics API manufacturing (≈50-55% of total consumption), Antibody‑Drug Conjugate (ADC) development and bioconjugation (≈15-20%), PROTAC (proteolysis‑targeting chimera) synthesis (≈10-15%), and specialised peptide library synthesis for drug discovery (≈10-15%). The compound has been explicitly employed in the SPPS of several high‑value peptide therapeutics and drug candidates, including ganirelix acetate (a GnRH antagonist for the treatment of prostate cancer).

1. Peptide Therapeutics API Manufacturing. Ganirelix acetate, a decapeptide used for the suppression of premature luteinising hormone (LH) surges in controlled ovarian hyperstimulation protocols, requires the incorporation of D‑lysine at a specific position to achieve the requisite metabolic stability and receptor selectivity. Fmoc-D-Lys(Boc)-OH is the preferred Fmoc SPPS building block for this incorporation. In addition to ganirelix, the compound is used in the manufacture of other peptide therapeutics where a single lysine residue must be positioned at a specific point in the sequence without side‑chain reactions. These include certain growth hormone‑releasing peptides (GHRPs), peptide‑based anticoagulants, and custom peptide APIs for clinical development.

2. Antibody‑Drug Conjugates (ADCs) and Peptide‑Drug Conjugates (PDCs). The ε‑NH₂ of lysine provides an orthogonal chemical handle for the attachment of payloads (cytotoxic agents, fluorophores, chelators, or oligonucleotides) after global deprotection and before or after cleavage from the resin. Fmoc-D-Lys(Boc)-OH is therefore used extensively in the synthesis of branched peptide scaffolds for multivalent display, in the construction of ADC linker peptides where a single amine is needed for conjugation, and in the development of site‑specific PDCs for targeted cancer therapy and molecular imaging.

3. PROTAC Synthesis for Targeted Protein Degradation. The lysine side chain provides a polyethylene glycol (PEG)‑like hydrophilic spacer between the two warheads (the E3 ligase ligand and the protein of interest binder). In PROTAC synthesis, Fmoc-D-Lys(Boc)-OH serves as the key branching unit because the ε‑NH₂ can be deprotected selectively with TFA and then used to attach the second warhead while the α‑NH₂ remains Fmoc‑protected and anchored to the resin. The D‑configuration of the lysine backbone is essential for certain PROTACs to achieve the correct spatial orientation of the two binding domains and to prevent unwanted proteolytic cleavage in biological media. The global PROTAC market was valued at approximately USD 1.2 billion in 2024 and is projected to reach USD 6.2 billion by 2030.

4. Peptide Library Synthesis for Drug Discovery. Fmoc-D-Lys(Boc)-OH is a standard building block for the construction of focused peptide libraries targeting GPCRs, ion channels, and enzyme active sites. In one‑bead‑one‑compound (OBOC) libraries and positional scanning synthetic combinatorial libraries (PS‑SCL), the compound serves as the dedicated N‑terminal building block for introducing a solubilising, positively charged residue that also provides an orthogonal handle for downstream functionalisation. By combining the Fmoc‑protected α‑amino group (for chain elongation) and the Boc‑protected ε‑amino group (for later deprotection and conjugation), the compound gives medicinal chemists a versatile platform for generating constrained peptides, stapled peptides, and peptide‑drug conjugates.

Major Market Participants and Supply Landscape

The global supply system for Fmoc-D-Lys(Boc)-OH follows the well‑established pattern of “specialised fine‑chemical and peptide‑building‑block manufacturers, with production and R&D supply concentrated in China, India, Europe, Japan, the Republic of Korea, and the United States.” Several major manufacturers offer the compound under various catalog numbers and purity grades, including Novabiochem (Merck), Bachem, Chem‑Impex, Alfa Aesar (Thermo Fisher Scientific), BOC Sciences, Glentham Life Sciences, Capot Chemical, Abbexa, BenchChem, and EvitaChem.

Novabiochem (Merck) supplies Fmoc-D-Lys(Boc)-OH as a standard building block for Fmoc SPPS, with ≥98% purity (HPLC) and a melting point of 120‑130°C. MedChemExpress offers a 99.77% purity grade, while other suppliers generally offer 98‑99% purity with enantiopurity ≥99.5% (L‑enantiomer ≤0.5%).

Shanghai XinChem Co., Ltd. (XinChem) has established a reliable, quality‑controlled supply chain for high‑purity Fmoc-D-Lys(Boc)-OH (CAS 92122‑45‑7). Our product meets rigorous pharmaceutical intermediate specifications — purity ≥98‑99% (HPLC), white to off‑white crystalline powder, molecular weight 468.54 g/mol, controlled residual solvents, low heavy metals (≤10 ppm, ICH Q3D compliant), and moisture <0.5% — fully compliant with global SPPS and peptide API manufacturing standards.

Regional Market Dynamics

Global demand for Fmoc-D-Lys(Boc)-OH shows a distinct regional pattern: Asia‑Pacific is the largest and fastest‑growing region for production and intermediate supply, North America and Europe lead in high‑purity R&D and pharmaceutical API manufacturing, and Latin America & Middle East/Africa follow as emerging growth regions.

Asia‑Pacific, and China in particular, has emerged as the dominant manufacturing hub for Fmoc‑protected and Boc‑protected amino acids and peptide building blocks. Chinese manufacturers have optimised large‑scale, fully automated SPPS processes and can produce high‑purity Fmoc-D-Lys(Boc)-OH at highly competitive prices, with capacities scaling from research grams to multi‑hundred‑kilogram industrial campaigns. India‘s rapidly expanding peptide API and generic injectable manufacturing sector also drives significant volume demand.

North America and Europe command the largest share of high‑purity R&D and commercial consumption (≥99%, enantio‑purity ≥99.5%), driven by the highest concentration of peptide drug discovery programmes, ADC development pipelines, and PROTAC research centres. Customer requirements in these regions are stringent: purity ≥99%, full traceability, ICH Q3D compliance for heavy metals, full impurity profiling (including residual solvents by GC‑headspace, related substances by HPLC‑UV, and enantiomeric purity by chiral HPLC), and cGMP documentation for pharmaceutical use. Japan and the Republic of Korea demand ultra‑high‑purity grades for advanced peptide drug development and ADC‑linker synthesis.

Storage, Stability, and Regulatory Considerations

Fmoc-D-Lys(Boc)-OH (CAS 92122‑45‑7) should be stored at 2‑8 °C in a tightly sealed, dry, light‑protected container, kept away from strong oxidising agents and strong bases. The compound is stable for up to three years when stored as a powder at –20 °C and for up to two years at 2‑8 °C. Solutions in DMSO are stable for up to one year at –80 °C.

In the European Union, Fmoc-D-Lys(Boc)-OH is subject to REACH regulations; importers and manufacturers must provide Safety Data Sheets (SDS). In the United States, it is regulated under TSCA as a research chemical; for use in pharmaceutical API synthesis, adherence to cGMP guidelines (21 CFR Parts 210/211) is required. In China, the compound is listed in the Inventory of Existing Chemical Substances (IECSC), with customs HS Code 29339900 (heterocyclic compounds with nitrogen hetero‑atom(s) only), and requires safety production licences for manufacturing facilities.

Future Outlook

The market outlook for Fmoc-D-Lys(Boc)-OH is tied to four core drivers: (1) the continued growth of the global peptide therapeutics market — projected to reach USD 1,640 million by 2034 at a CAGR of 9.39%, where D‑amino acid building blocks are essential for improving metabolic stability; (2) the explosive growth of the PROTAC field, where glutarimide‑based cereblon binders and amino acid branching units are the dominant E3 ligase recruiting warheads; (3) the expansion of Asian CRO/CDMO sectors supplying intermediates to global pharmaceutical companies; and (4) the increasing adoption of D‑lysine in ADC linker synthesis for site‑specific conjugation to antibodies.

Shanghai XinChem Co., Ltd. (XinChem)

As a world‑leading supplier of pharmaceutical intermediates and heterocyclic building blocks, Shanghai XinChem Co., Ltd. (XinChem) has always focused on the innovative needs of the peptide API manufacturing, ADC development, and PROTAC drug discovery industries.

1. Technical Advantages

High Purity & Consistent Quality: Our product achieves purity ≥98‑99% (HPLC), white to off‑white crystalline powder, molecular weight 468.54 g/mol, melting point 120‑140 °C, and moisture <0.5 % (KF titration). Enantiomeric purity: L‑enantiomer ≤0.5%, D‑isomer ≥99.5% (by chiral HPLC).
Low Impurity Profile: Strict control of residual solvents (<0.5% total), heavy metals (≤10 ppm, ICH Q3D compliant), and related substances by HPLC‑UV ensures high synthetic performance for SPPS and peptide API manufacturing.
Full Regulatory Documentation: The compound is tested for full ICH Q3C (residual solvents), ICH Q3D (heavy metals), and USP residual solvents, providing full traceability to primary analytical standards.
Batch‑to‑Batch Uniformity: Rigorous analytical testing (HPLC, UPLC, NMR, LC‑MS, heavy metals by ICP‑MS, residual solvents by GC‑headspace, Karl Fischer titration) guarantees consistent quality and reproducible yields across all production lots.

2. Product Advantages

Standard N‑Fmoc Building Block for SPPS: Directly used as the key N‑Fmoc amino acid building block in fully automated and manual SPPS workflows, and in large‑scale solution‑phase synthesis for generic peptide APIs.
Orthogonal ε‑Boc Protection: The Boc side chain remains intact during Fmoc removal (piperidine, 20% in DMF) and during coupling steps, preventing unwanted side reactions and enabling efficient synthesis of lysine‑rich and aggregation‑prone peptide sequences.
High Coupling Efficiency: Compatible with standard activating reagents (HATU, HBTU, COMU, PyBOP, DIC, DIC/Oxyma, DIC/HOBt), routinely achieving coupling yields ≥98% in SPPS.
Flexible Packaging Options: 1 g, 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 fibre drums (industrial). Full custom packaging available for pharmaceutical campaigns.
Reliable Supply Chain: Annual capacity in the multi‑metric‑ton range, with dedicated temperature‑controlled warehousing (2‑8 °C, dry, light‑protected, sealed containers) and just‑in‑time delivery capabilities.

3. Application Fields

Pharmaceutical Intermediates: Key building block for ganirelix acetate (GnRH antagonist for prostate cancer), GHRPs, peptide‑based anticoagulants, and custom peptide APIs for oncology, metabolic disorders, and infectious diseases.
Antibody‑Drug Conjugates (ADCs) & Peptide‑Drug Conjugates (PDCs): ε‑NH₂ as orthogonal handle for payload attachment (cytotoxic agents, fluorophores, chelators) in ADC linker‑peptide synthesis, branched peptide scaffolds for multivalent display, and site‑specific PDCs for targeted cancer therapy.
PROTAC Synthesis: Key branching unit and lysine‑derived hydrophilic spacer for heterobifunctional protein degrader assembly.
Solid‑Phase Peptide Synthesis (SPPS): Standard building block for introduction of D‑lysine residues in Boc/Bzl and Fmoc/t‑Bu strategies, reference material for coupling reagent optimisation, and protected amino acid unit for stepwise peptide chain assembly.
Custom Peptide Synthesis: CRO/CDMO custom‑synthesised peptides, one‑bead‑one‑compound (OBOC) libraries, positional scanning synthetic combinatorial libraries (PS‑SCL), and constrained or stapled peptide libraries.

4. Service Support
Our technical team provides full impurity profiling (HPLC, LC‑MS, enantiomeric purity by chiral HPLC, residual solvents by GC‑headspace, heavy metals by ICP‑MS, moisture by KF titration), 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 Fmoc‑protected and Boc‑protected amino acid derivatives, cold‑chain logistics, and just‑in‑time delivery.

5. Why Choose XinChem

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

Post time: Jun-01-2026

The Essential Chiral Building Block for Peptide Therapeutics, ADCs, and PROTACs:Fmoc-D-Lys(Boc)-OH (CAS 92122-45-7)