L-isoleucine methyl ester hydrochloride is a derivative of the proteinogenic amino acid L-isoleucine in which the carboxyl group is esterified as a methyl ester and the compound is present as a hydrochloride salt. The molecule retains the free amino functionality as an ammonium chloride salt while bearing a branched aliphatic side chain characteristic of isoleucine, and the methyl ester masks the carboxylate to alter polarity and reactivity relative to the free amino acid. In peptide and amino acid synthesis, this esterified, salt-form amino acid intermediate is used to support controlled incorporation of the isoleucine residue and to facilitate stepwise coupling strategies while the protected carboxyl functionality reduces undesired side reactions during assembly of peptide derivatives.
L-isoleucine methyl ester hydrochloride is the methyl ester salt of L-isoleucine, retaining the chiral α-carbon stereochemistry characteristic of the L-amino acid. The molecule presents a protected carboxyl equivalent as a methyl ester hydrochloride, alongside a free or ester-activated amino functionality under salt conditions, and a hydrophobic isobutyl side chain that influences conformational preferences in peptide and scaffold synthesis. The ester group enables controlled downstream transformations such as ester-to-amide conversion and selective hydrolysis, while the hydrochloride counterion supports handling of the amino functionality during coupling chemistry. As a chiral amino acid ester intermediate, it participates in stereochemically defined peptide building block preparation and provides a practical entry point to L-isoleucine derivatives used in both synthetic methodology development and industrial fine chemical workflows.
1. Peptide Coupling Chemistry
L-isoleucine methyl ester hydrochloride is applied in peptide synthesis workflows where an amino acid ester serves as a precursor to amide-forming derivatives. The combination of the L-configured α-stereocenter and the carboxyl equivalent as a methyl ester supports conversion into activated coupling partners, including routes that generate amide bonds through ester activation or subsequent hydrolysis to the corresponding acid prior to coupling. Salt-state amino functionality and the ester handle can be integrated into stepwise assembly strategies for short peptide segments and protected amino acid intermediates. Downstream use commonly includes preparation of isoleucine-containing peptide analogs and side-chain-defined fragments for library synthesis and sequence optimization studies in biochemical research.
2. Protected Amino Acid Intermediate
L-isoleucine methyl ester hydrochloride is suitable for manufacturing and laboratory preparation of protected L-isoleucine derivatives used to control chemoselectivity during peptide construction. The methyl ester can be maintained through N-protection steps, enabling orthogonal protection strategies where the amino group is protected for coupling while the carboxyl functionality remains in an ester form until the desired stage. Hydrochloride salt formation supports reproducible handling of the amino group during protection and purification operations, reducing variability associated with free-base forms. Resulting downstream intermediates include N-protected isoleucine esters and related building blocks that can undergo deprotection and coupling under standard peptide synthesis conditions.
3. Chiral Building Block Synthesis
L-isoleucine methyl ester hydrochloride functions as a chiral amino acid ester intermediate for stereoselective synthesis of isoleucine-derived scaffolds and non-natural analogs. The retained L-configuration at the α-carbon provides a stereochemical anchor for subsequent transformations such as ester hydrolysis, oxidation/reduction of functional handles introduced later, and conversion to amide or urea linkages. The hydrophobic isobutyl side chain can be leveraged to tune lipophilicity and conformational behavior in peptidomimetics and fragment-like modules used in molecular design. Downstream formation includes chiral intermediates for SAR studies, stereochemically defined peptidomimetic construction, and synthesis of isoleucine-containing chemical entities used as reference standards or research probes.
4. Process Chemistry Intermediate
L-isoleucine methyl ester hydrochloride is relevant to process chemistry intermediate preparation where amino acid ester handling and conversion to downstream derivatives are required at scale. The methyl ester provides a controllable carboxyl equivalent that can be converted to acids or amides through hydrolysis or activation steps in a manufacturing sequence, while the hydrochloride salt form supports aqueous workup compatibility and stable storage of the amino component. The molecule's single stereocenter and straightforward functional group set facilitate route design for producing protected amino acid intermediates and peptide coupling-ready materials with defined stereochemistry. Downstream utility includes use in specialty chemical production for peptide building blocks, contract manufacturing of amino acid derivatives, and consistent feedstock generation for industrial peptide and peptidomimetic supply chains.
5. Analytical Reference Standards
L-isoleucine methyl ester hydrochloride is used in analytical research contexts as a structurally defined chiral reference material for method development and impurity profiling. The presence of both the methyl ester and the amino salt state enables chromatographic and spectrometric characterization that distinguishes it from the corresponding free acid, free amino acid, or fully protected peptide-grade building blocks. Ester hydrolysis behavior and salt-state properties can be monitored to validate sample preparation workflows and to track conversion steps in peptide synthesis intermediate streams. Downstream applications include calibration support for chiral HPLC/UPLC method development, quality control of intermediate batches, and verification of stereochemical integrity in L-isoleucine derivative manufacturing.
4. The spatiotemporal control of signalling and trafficking of the GLP-1R
5. Autoinhibition and phosphorylation-induced activation of phospholipase C-γ isozymes
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