Fmoc-L-Lys(N3)-OH

Fmoc-L-Lys(N3)-OH is an Fmoc-protected L-lysine derivative bearing an azide substituent on the side-chain ε-amino group, providing a chiral amino acid scaffold with orthogonal functional handles for peptide and conjugation chemistry. The molecule contains the Fmoc carbamate on the α-amino group and a free carboxylic acid at the α-position, enabling standard peptide coupling while maintaining the azide as a chemically stable, bioorthogonal reactive group. The ε-azide (N3) can participate in strain-promoted or copper-catalyzed azide-alkyne cycloaddition workflows after deprotection and incorporation into peptides or linkers. Stereochemical integrity at the lysine α-center supports predictable amide bond formation and downstream fragment assembly in synthetic organic chemistry and biochemical research.

1. Peptide Synthesis

Fmoc-L-Lys(N3)-OH is used in solid-phase peptide synthesis where the Fmoc-protected α-amino group supports iterative coupling to build peptide sequences with a lysine residue at defined positions. The free carboxylic acid and protected amine enable routine amide bond formation under peptide synthesis conditions, while the side-chain ε-azide remains available for post-synthetic functionalization. Fmoc removal exposes the α-amine for controlled chain elongation without disturbing the azide handle, supporting orthogonally protected amino acid chemistry. Incorporation of this lysine analog enables azide-tagged peptides for subsequent conjugation, crosslinking, or attachment of imaging and affinity motifs, aligning peptide construction with downstream molecular modification.

2. Bioconjugation Chemistry

Fmoc-L-Lys(N3)-OH serves as a side-chain azide precursor for bioconjugation workflows that require site-specific attachment points on peptides, proteins, or biomolecule-derived constructs. The ε-azide provides a controlled reactive group that can be engaged after peptide assembly, allowing conjugation strategies that preserve peptide backbone integrity and stereochemical definition. The Fmoc-protected α-amino group supports incorporation into larger biomolecular scaffolds, while the carboxylate functionality supports coupling-derived incorporation rather than random labeling. Downstream formation of azide-functional conjugates can be applied to chemical biology studies, affinity probe generation, and engineered biomolecule labeling where azide-alkyne cycloaddition chemistry is used to install functional moieties.

3. Peptidomimetics And SAR Studies

Fmoc-L-Lys(N3)-OH supports peptidomimetic and structure-activity relationship studies by enabling the placement of a lysine-derived azide functionality within peptide-like frameworks. The side-chain azide can be transformed into triazole-linked substituents, linkers, or constrained analogs that modulate sterics and electronic properties around the lysine position. The protected amino acid format facilitates systematic variation of substituents through modular coupling and post-assembly derivatization, supporting SAR mapping of functional group placement and linker geometry. Resulting azide-derived analogs can function as chemically defined intermediates for library synthesis and scaffold diversification in medicinal chemistry and biochemical research.

4. Side-Chain Functionalization

Fmoc-L-Lys(N3)-OH is suitable for synthetic organic chemistry routes that require orthogonal functional group staging, combining an Fmoc-protected amine for controlled peptide coupling with a side-chain azide for later transformation. The ε-azide can undergo selective click chemistry to introduce alkynyl fragments, fluorescent tags, affinity groups, or polymerizable handles after the amino acid has been incorporated into a peptide or protected intermediate. The presence of the α-carboxylic acid supports conversion into activated derivatives when preparing larger building blocks, while the azide's stability under common peptide handling conditions helps maintain a single reactive site. Downstream derivatization enables generation of functionalized peptide analogs and chemical intermediates for materials and conjugate synthesis.

5. Pharmaceutical Manufacturing Intermediates

Fmoc-L-L-Lys(N3)-OH can be applied as a manufacturing-oriented peptide building block for producing defined, azide-functional intermediates used in the preparation of peptide-based reagents and processable conjugates. The Fmoc protection strategy supports reliable protection/deprotection cycles compatible with peptide assembly workflows, while the azide functionality provides a handle for controlled downstream coupling steps that can be integrated into manufacturing sequences. The lysine stereocenter and protected α-amino group help ensure consistent incorporation into peptide fragments, supporting reproducible intermediate generation for fine chemical synthesis. Use in industrial peptide construction can support the preparation of well-defined functional molecules that require orthogonal reactivity for subsequent derivatization and controlled assembly into larger structures.

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