(S)-Alloc-Lys-OH·HCl: Properties, Uses & FAQs

(S)-6-(((Allyloxy)carbonyl)amino)-2-aminohexanoic acid hydrochloride is an orthogonally protected L-lysine derivative in which the epsilon-amine bears an allyloxycarbonyl (Alloc) protecting group, making it a versatile building block for solid-phase and solution-phase peptide synthesis where selective side-chain deprotection is required.

Chemical Name

(S)-6-(((Allyloxy)carbonyl)amino)-2-aminohexanoic acid hydrochloride

Common Abbreviation

Alloc-Lys-OH·HCl (H-Lys(Alloc)-OH·HCl)

SKU

C732729

Protecting Group Chemistry

Allyloxycarbonyl (Alloc) on the ε-amine; alpha-amine free as HCl salt

Deprotection Method

Palladium(0)-catalyzed allyl transfer (e.g., Pd(PPh3)4, nucleophilic scavenger)

Stereochemistry

S-configuration (L-lysine backbone)

Supplier

Aladdin Scientific

What Is (S)-6-(((Allyloxy)carbonyl)amino)-2-aminohexanoic acid hydrochloride?

(S)-6-(((Allyloxy)carbonyl)amino)-2-aminohexanoic acid hydrochloride, commonly abbreviated as H-Lys(Alloc)-OH·HCl or Alloc-Lys-OH·HCl, is a selectively side-chain-protected derivative of the essential amino acid L-lysine. In this compound, the epsilon (ε) amino group of lysine is masked by an allyloxycarbonyl (Alloc) carbamate protecting group, while the alpha (α) amino group is presented as a free base stabilized as its hydrochloride salt. The Alloc group is valued in peptide chemistry because it is orthogonal to both acid-labile protecting groups (e.g., Boc, tBu) and base-labile protecting groups (e.g., Fmoc), enabling highly selective on-resin or in-solution deprotection. The compound is a white to off-white solid that should be stored under cool, dry conditions away from moisture and light to preserve integrity.

Role in Peptide Synthesis and Orthogonal Protection Strategies

The primary application of H-Lys(Alloc)-OH·HCl is as a building block in solid-phase peptide synthesis (SPPS) and solution-phase peptide coupling reactions. Orthogonal protection refers to the simultaneous use of multiple protecting groups that can each be removed independently under different, non-interfering conditions. The Alloc group is selectively removed by palladium(0) complexes — most commonly tetrakis(triphenylphosphine)palladium(0) [Pd(PPh₃)₄] — in the presence of a nucleophilic scavenger such as morpholine, dimethylbarbituric acid, or dimedone, which trap the released allyl species. This mild, metal-mediated deprotection leaves acid-labile (Boc, tBu) and base-labile (Fmoc) protecting groups completely intact.

A key use case is the construction of branched or cyclic peptides, lactam-bridged analogues, and peptides bearing site-specific modifications on the lysine side chain, such as lipidation, PEGylation, fluorescent labeling, or isopeptide bond formation. By incorporating H-Lys(Alloc)-OH, researchers can unmask only the desired ε-amine at a defined sequence position during or after chain assembly, coupling it selectively to activate acids or other electrophiles.

Handling, Storage, and Safety Considerations

Like most amino acid derivatives, (S)-6-(((Allyloxy)carbonyl)amino)-2-aminohexanoic acid hydrochloride should be handled with standard laboratory precautions. Wear appropriate personal protective equipment (PPE) including gloves, lab coat, and eye protection. Avoid inhalation of dust or aerosols. The compound should be stored in a tightly sealed container at 2–8 °C or as specified on the product label, protected from moisture and light. Prolonged exposure to air or humidity may cause degradation or discoloration. Upon receipt, inspect the material and record the lot number and expiry date. For long-term storage, aliquoting into inert atmosphere vials under argon or nitrogen is recommended. Consult the Safety Data Sheet (SDS) provided by Aladdin Scientific for comprehensive hazard, first-aid, and disposal information before use.

Quality, Purity, and Analytical Characterization

Aladdin Scientific supplies (S)-6-(((Allyloxy)carbonyl)amino)-2-aminohexanoic acid hydrochloride (SKU C732729) as a research-grade reagent. Typical quality attributes evaluated for amino acid protecting-group derivatives include: chemical purity assessed by HPLC (reverse-phase C18), structural confirmation by ¹H NMR and ¹³C NMR spectroscopy, identity confirmation by high-resolution mass spectrometry (HRMS) or LC-MS, optical rotation to confirm S-stereochemistry, and water content by Karl Fischer titration. Certificate of Analysis (CoA) data including lot-specific purity, appearance, and analytical test results are available upon request from Aladdin Scientific. Researchers requiring the highest purity for sensitive biological assays should confirm the CoA values prior to use and contact technical support if additional characterization data are needed.

Ordering and Availability from Aladdin Scientific

(S)-6-(((Allyloxy)carbonyl)amino)-2-aminohexanoic acid hydrochloride is available from Aladdin Scientific under SKU C732729. To place an order, visit the Aladdin Scientific website, search by SKU or product name, select the desired pack size and quantity, and proceed through the standard checkout process. For bulk quantities, custom pack sizes, or institutional procurement inquiries, contact the Aladdin Scientific sales team directly. Registered account holders may benefit from reward points, promotional pricing, and streamlined reordering. All orders are subject to Aladdin Scientific's standard terms regarding payment, shipping, and returns — please review the relevant policies on the website or contact customer service for assistance.

Frequently asked questions

What does the Alloc protecting group do, and why is it useful for lysine?

The allyloxycarbonyl (Alloc) group protects the ε-amine of lysine as a stable carbamate that resists both acidic (TFA, HCl) and basic (piperidine) conditions used routinely in Fmoc and Boc SPPS. It is removed selectively by Pd(0) catalysis under mild, near-neutral conditions, making it orthogonal to Fmoc and Boc strategies and ideal for introducing site-specific side-chain modifications such as lactam bridges, lipidation, or labeling during or after chain assembly.

How is the Alloc group removed from H-Lys(Alloc)-OH after incorporation into a peptide?

The Alloc group is removed by treatment with a palladium(0) source, most commonly tetrakis(triphenylphosphine)palladium [Pd(PPh₃)₄], in the presence of a nucleophilic allyl scavenger such as morpholine, dimethylbarbituric acid, or phenylsilane in a suitable solvent (e.g., DCM or THF). The Pd(0) undergoes oxidative addition into the allyl–oxygen bond, and the scavenger traps the π-allyl–Pd complex, regenerating the free amine. This reaction can be performed on-resin in SPPS or in solution. Care should be taken to degas solvents to protect the Pd catalyst from oxidative deactivation.

Is H-Lys(Alloc)-OH·HCl compatible with standard Fmoc SPPS coupling reagents?

Yes. Because only the ε-amine is Alloc-protected and the α-carboxyl is free, H-Lys(Alloc)-OH·HCl can be activated and coupled using standard Fmoc SPPS reagents such as HATU, HBTU, DIC/Oxyma, or PyBOP in the presence of a base (e.g., DIPEA or NMM). After coupling, Fmoc removal from the alpha position proceeds normally with piperidine. Researchers should note that the hydrochloride salt form means an additional equivalent of base may be required during coupling to neutralize the HCl.

What are the recommended storage conditions for SKU C732729?

The compound should be stored in a tightly sealed container at 2–8 °C, protected from moisture, light, and air. For long-term storage, transfer to inert-atmosphere (argon or nitrogen) vials is advisable. Always allow the container to equilibrate to room temperature before opening to prevent condensation. Refer to the product label and the Aladdin Scientific Certificate of Analysis for lot-specific storage recommendations.

Can this compound be used for bioconjugation or labeling applications beyond traditional SPPS?

Yes. The Alloc-protected lysine derivative is well suited for solution-phase bioconjugation workflows where selective, mild deprotection of a lysine side chain amine is needed without disturbing other protecting groups or functional handles present on the molecule. Applications include the synthesis of antibody-drug conjugate (ADC) linker-payloads, peptide–lipid conjugates, fluorescently labeled peptides, and cyclic peptides formed via on-resin lactamization. The orthogonality and Pd(0)-selectivity of the Alloc group make it attractive in multi-step synthetic sequences requiring precise chemoselective control.

References

1. Kates, S.A.; Albericio, F. (Eds.) Solid-Phase Synthesis: A Practical Guide. Marcel Dekker, 2000. (General reference on orthogonal protecting group strategies in SPPS.)
2. Lauer, J.L.; Fields, C.G.; Fields, G.B. Sequence dependence of aspartimide formation during 9-fluorenylmethoxycarbonyl solid-phase peptide synthesis. Lett. Pept. Sci. 1994, 1, 197–205. (Cited as context for side-chain protection strategies.)
3. Dessolin, M.; Guillerez, M.-G.; Thieriet, N.; Guibé, F.; Loffet, A. Use of alloc group in solution peptide synthesis. Tetrahedron Lett. 1995, 36, 5741–5744.
4. Guibé, F. Allylic protecting groups and their use in a complex environment. Part II: Allylic protecting groups and their removal through catalytic organometallic procedures. Tetrahedron 1998, 54, 2967–3042.

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.