L-Leucine methyl ester hydrochloride is a methyl ester derivative of the amino acid leucine, featuring an aliphatic isobutyl side chain and a carboxyl group converted to a methyl ester while retaining the amino functionality as a hydrochloride salt. The molecule bears an ester carbonyl and a protonated amino group (as the chloride salt), and the "L-" designation indicates the stereochemical form at the alpha carbon consistent with L-leucine. It is used as a protected, esterified leucine building block in peptide and amide synthesis workflows where esterification can modulate solubility and reactivity, and where the salt form supports handling of the amino functionality during coupling or subsequent transformations.
CAT No: CP01331
CAS No:7517-19-3
Synonyms/Alias:7517-19-3;L-Leucinemethylesterhydrochloride;H-Leu-OMe.HCl;(S)-Methyl2-amino-4-methylpentanoatehydrochloride;MethylL-leucinatehydrochloride;leucinemethylesterhydrochloride;MFCD00012494;H-Leu-OMeinvertedexclamationmarkcurrencyHCl;NH-Leu-OMe.HCl;PubChem10892;H-Leu-OMehydrochloride;AC1MC3ER;H-L-LEU-OMEHCL;L1002_ALDRICH;SCHEMBL76795;methylleucinatehydrochloride;KSC379G7J;CHEMBL1222002;CTK2H9374;DODCBMODXGJOKD-RGMNGODLSA-N;MolPort-003-937-804;BB_NC-1737;ACT08766;ANW-36569;AKOS015845882
L-Leucine methyl ester hydrochloride is the methyl ester hydrochloride salt of L-leucine, retaining the leucine side chain with an isobutyl group and the stereogenic α-carbon in the L-configuration. The molecule presents a protected carboxyl functionality as a methyl ester while the amino group is present as a salt form, which modulates nucleophilicity and improves handling during peptide coupling and derivatization sequences. The ester carbonyl enables controlled transformations to amides, hydrazides, or activated acyl intermediates, while the branched hydrophobic side chain supports incorporation into peptide scaffolds and hydrophobic binding motifs in synthetic libraries. As a chiral amino acid ester intermediate, it can be used to build protected amino acid derivatives and downstream peptide building blocks with stereochemical integrity.
1. Peptide Coupling Chemistry
L-Leucine methyl ester hydrochloride is used in peptide synthesis workflows where amino acid ester intermediates are converted into coupling-ready forms for amide bond formation. The L-leucine stereocenter and the methyl ester carbonyl provide a defined chiral acyl component, while the hydrochloride salt state supports preparation of N-protected derivatives prior to coupling. Ester-to-amide conversion strategies enable formation of C-terminal peptide segments or incorporation into short peptide fragments compatible with standard peptide coupling reagents. Downstream, the resulting peptide building blocks can be extended into larger sequences for structure-activity relationship studies and synthetic peptide material generation.
2. Protected Amino Acid Derivatization
L-Leucine methyl ester hydrochloride serves as a practical starting material for N-protected amino acid derivative preparation, including routes that generate Boc-, Cbz-, or Fmoc-type protected leucine esters depending on the selected protection scheme. The amino functionality as a hydrochloride salt can be neutralized and then protected, while the methyl ester remains available for selective functional group interconversions. The ester group can be retained for later C-terminal modification or transformed into activated species for sequential assembly of peptide analogs and chiral intermediates. This protection and functional-group management supports controlled stereochemical outcomes and predictable reactivity in fine chemical synthesis.
3. Chiral Intermediate For SAR Libraries
L-Leucine methyl ester hydrochloride is applicable to combinatorial and SAR-oriented synthesis where branched hydrophobic amino acid motifs are incorporated to probe binding and conformational effects. The isobutyl side chain and L-configuration enable consistent placement of leucine-derived steric and hydrophobic features into peptide-like scaffolds and peptidomimetic fragments. The methyl ester can be converted into amide or carboxylate forms used to diversify terminal functionalities across a library of analogs. Generated derivatives can then be used as chemical probes in biochemical research, supporting systematic structure-activity relationship studies without altering the leucine stereochemical identity.
4. Enzyme Substrate Analogues
L-Leucine methyl ester hydrochloride can be employed to construct amino acid ester or amino acid-derived amide substrates used in enzyme studies that involve protease-like or peptidase-like recognition of hydrophobic residues. The methyl ester functionality provides a handle for preparing substrate analogues that reflect leucine's side-chain hydrophobicity and stereochemical preferences at the α-position. Ester-to-amide or ester-to-activated-acyl transformations can yield compounds suitable for mechanistic evaluation of substrate specificity in vitro assay formats. Downstream derivatives derived from this chiral amino acid ester can also serve as reference materials for method development in biochemical research.
5. Pharmaceutical Intermediate Preparation
L-Leucine methyl ester hydrochloride is suitable for industrial intermediate preparation where chiral amino acid ester chemistry is used to access downstream acyl building blocks for active pharmaceutical ingredient synthesis. The methyl ester can function as a protected carboxyl equivalent during multi-step routes, allowing controlled conversion to amides, acid chlorides, or other acyl derivatives under process-compatible conditions. The hydrochloride salt form supports reproducible handling and can be integrated into manufacturing sequences that require staged protection and deprotection of amino and carboxyl functionalities. Resulting leucine-derived intermediates can then be directed toward peptide-like fragments, chiral auxiliaries, or side-chain-functionalized moieties used in pharmaceutical intermediate portfolios.
6. Analytical Standards And Method Development
L-Leucine methyl ester hydrochloride is used in analytical research and method development as a chiral reference material for monitoring amino acid ester transformations and stereochemical integrity during synthesis. The defined L-configuration and the ester hydrochloride form provide a consistent chemical identity for chromatographic and spectrometric characterization of leucine-derived intermediates. Ester-to-acid or ester-to-amide conversion products generated from this starting material can serve as calibration points for quantifying reaction progress in amino acid derivatization workflows. Broader relevance includes quality control support for peptide building block preparation and verification of chiral amino acid intermediate profiles in applied chemical manufacturing.
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