L-lysine ethyl ester dihydrochloride is a protected amino acid derivative in which the α-carboxyl group of L-lysine is converted to an ethyl ester while the side-chain ε-amino group remains free, and the compound is present as a dihydrochloride salt. The molecule therefore bears an α-amino group and an ε-amino group that are protonated under hydrochloride salt conditions, paired with an esterified carboxyl functionality that reduces carboxyl reactivity relative to the free amino acid. It is used in amino acid and peptide synthesis workflows as an esterified lysine building block where salt formation and ester protection support controlled handling and chemoselective coupling to assemble lysine-containing peptide intermediates.
CAT No: CP01472
CAS No:3844-53-9
Synonyms/Alias:3844-53-9;L-Lysineethylesterdihydrochloride;H-Lys-OEt.2HCl;EthylL-lysinatedihydrochloride;(S)-Ethyl2,6-diaminohexanoatedihydrochloride;H-Lys-OEt·2HCl;ethyl(2S)-2,6-diaminohexanoatedihydrochloride;EthylL-lysinateHCl;H-LYS-OET2HCL;PubChem18980;H-Lys-OEt?currency2HCl;AC1Q3B1Z;KSC491O3H;62880_ALDRICH;L5754_SIGMA;SCHEMBL213479;62880_FLUKA;CTK3J1733;lysineethylesterdihydrochloride;DZIYAIZKJOHVQC-KLXURFKVSA-N;MolPort-003-937-839;AC1L3277;EINECS223-340-3;AR-1I9778
L-lysine ethyl ester dihydrochloride is the ethyl ester hydrochloride salt of L-lysine, retaining the canonical lysine backbone with a stereogenic center at the alpha carbon and a terminal ε-amino side chain. The molecule bears an esterified carboxyl group and two chloride counterions that protonate the basic amine functions, producing a water-compatible, salt-form intermediate for downstream peptide and derivatization chemistry. The protected/activated functional-group pattern combines an ester handle for controlled acylation chemistry with a protonated side-chain amine that can be selectively deprotonated, protected, or converted to amide, carbamate, or other nitrogen-linked motifs. The chiral amino acid ester format supports stereochemically consistent building-block incorporation into peptide coupling sequences and synthetic routes that require a lysine-derived intermediate with defined nitrogen reactivity.
1. Protected Lysine Building Block
L-lysine ethyl ester dihydrochloride is applied in peptide building-block preparation and protected amino acid synthesis workflows where lysine side-chain nitrogen chemistry must be orchestrated. The ethyl ester enables carboxyl activation for peptide coupling while the ε-amino group, present as a salt, can be managed through base-mediated deprotonation and subsequent N-protection strategies such as Boc or Cbz installation depending on the coupling and deprotection scheme. The preserved L-configuration at the alpha carbon supports stereochemical fidelity during amide bond formation, minimizing racemization risk in chiral peptide assembly. Lysine-derived intermediates generated from this ester can be carried into stepwise SPPS or solution-phase fragment coupling to access defined lysine-containing sequences and analogs. The salt-form starting material aligns with common amino acid intermediate logistics in fine chemical synthesis, where controlled nitrogen protection and ester-to-acid conversion are recurring process steps.
2. Peptide Coupling Chemistry
L-lysine ethyl ester dihydrochloride is utilized in peptide coupling chemistry for constructing lysine-terminated fragments and generating C-terminal lysine residues after ester hydrolysis. The carboxylate equivalent provided by the ethyl ester participates in standard activation modes to form amide bonds, while the protonated amine functionality can be selectively addressed to prevent undesired N-acylation during coupling. The molecule's two hydrochloride salts facilitate handling as a chiral, nitrogen-rich intermediate that can be converted into N-protected lysine esters or acids for orthogonal protection strategies. Downstream, the lysine residue can be incorporated into peptide libraries, enabling systematic variation of side-chain-linked functionalities through post-coupling derivatization. The chiral amino acid ester format thus serves as a practical entry point for peptide construction routes requiring reliable control over lysine's bifunctional nitrogen reactivity.
3. Side-Chain Functionalization
L-lysine ethyl ester dihydrochloride is applied to side-chain functionalization and amino acid derivatization programs that target the ε-amino group for conjugation-ready handles. The salt-protonated ε-amine can be converted into reactive intermediates through controlled deprotonation followed by acylation, carbamylation, or formation of protected derivatives that withstand subsequent steps. The ester group can be retained temporarily to enable selective transformations on the side chain while maintaining a defined carboxyl reactivity state for later conversion to acids or activated derivatives. Lysine side-chain modifications derived from this intermediate can feed into peptidomimetic construction, linker installation, and generation of amide or urea motifs that influence molecular recognition in biochemical assays. The combination of chiral backbone integrity and functional nitrogen chemistry supports downstream formation of functionalized lysine analogs used in synthetic organic chemistry and applied biochemical research.
4. Chemical Biology Labeling
L-lysine ethyl ester dihydrochloride is suitable for chemical biology workflows that require lysine-derived motifs for labeling, tagging, and biomolecule modification strategies. The ε-amino group provides a chemically addressable nucleophile for forming amide or carbamate linkages with electrophilic labeling reagents, while the ester functionality can be converted to carboxylic acid or activated forms to enable controlled coupling to carriers or scaffolds. The dihydrochloride salt form improves handling of the basic amino acid during derivatization sequences, supporting reproducible preparation of labeled intermediates for downstream conjugation. Lysine-containing building blocks obtained from this ester can be incorporated into peptide probes or used to generate lysine-functional linkers for studying protein interactions and binding-site chemistry. The stereodefined L-lysine backbone ensures consistent structural presentation when lysine residues are incorporated into peptide-based chemical tools.
5. Pharmaceutical Intermediate Preparation
L-lysine ethyl ester dihydrochloride is employed as a chiral intermediate in pharmaceutical intermediate preparation and process chemistry for manufacturing routes that build lysine-containing fragments. The amino acid ester format supports conversion to protected lysine acids or N-protected derivatives that can be coupled into larger intermediates, including peptide-like structures and nitrogen-rich scaffolds. The presence of protonated amines as hydrochloride salts facilitates storage and metering in manufacturing environments, while the ester group provides a handle for activation and subsequent hydrolysis or transesterification steps in controlled process sequences. Side-chain nitrogen derivatization enables installation of amide, carbamate, or other nitrogen functionalities consistent with medicinal chemistry SAR studies and solid intermediate generation. The compound's chiral, lysine-based structure therefore aligns with industrial fine chemical synthesis needs where robust protection/deprotection logic and stereochemical consistency are required.
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