H-DL-Met-OEt · HCl is a hydrochloride salt of the amino acid ester derived from DL-methionine, featuring a thioether-containing methionine side chain and an ethyl ester at the carboxyl terminus. The molecule contains an amino group (as the hydrochloride-associated form) and a carboxyl functionality masked as the OEt ester, with the DL designation indicating a racemic mixture of stereoisomers at the alpha carbon. It is used as a protected/derivatized methionine building block in peptide and amino acid derivative synthesis, as well as in solution-phase or solid-phase assembly workflows where an esterified carboxyl group and controlled salt form can support handling and downstream transformations.
H-DL-Met-OEt · HCl is a hydrochloride salt of a racemic methionine ethyl ester, featuring an amino acid ester (OEt) that masks the carboxylate as an ester while retaining a protonated amine under acidic conditions. The methionine side chain contains a thioether (-S-CH3) that can participate in selective oxidation, alkylation, or controlled thioether-to-sulfoxide/sulfone transformations used for downstream functionalization. The DL stereochemical designation indicates a racemic mixture at the α-carbon, making the material suitable for method development and intermediate preparation where stereochemical resolution can be introduced later or where racemate incorporation is acceptable. The presence of HCl supports salt formation for handling and can influence coupling and deprotection logic in peptide-building workflows.
1. Peptide Coupling Chemistry
H-DL-Met-OEt · HCl is applied in peptide synthesis planning as a protected amino acid ester building block where the ethyl ester can be converted to an activated carboxyl derivative for coupling to amines. The amino hydrochloride form provides a defined amine reactivity profile for standard peptide coupling sequences, while the methionine thioether side chain remains chemically addressable for orthogonal transformations. Racemic (DL) stereochemistry supports library-oriented or process-development studies that evaluate coupling conditions without requiring enantiopure material at the earliest stage. Downstream, the ester functionality can be hydrolyzed or transesterified to align with C-terminal modification strategies in peptide fragment assembly.
2. Side-Chain Thioether Functionalization
H-DL-Met-OEt · HCl supports synthetic organic chemistry routes that exploit the methionine thioether for late-stage functional group interconversion. The thioether can undergo oxidation to sulfoxide or sulfone derivatives, enabling polarity tuning and controlled reactivity for subsequent derivatization, including electrophile-mediated transformations or nucleophile-directed substitutions where appropriate. The ester and ammonium salt features facilitate protection/deprotection sequencing, allowing the α-amino functionality and carboxyl equivalent to be managed independently during side-chain modification. The resulting sulfur-functionalized amino acid derivatives can then be carried into peptide analog construction, chiral auxiliary development, or scaffold diversification for structure-activity relationship studies.
3. Chiral Resolution Intermediate
H-DL-Met-OEt · HCl is suitable as a chiral amino acid intermediate feedstock in workflows that begin with a racemate and introduce stereochemical control through resolution or asymmetric conversion steps downstream. The α-amino ester framework enables formation of diastereomeric derivatives with chiral acids or auxiliaries, and the methionine side-chain thioether tolerates many resolution and derivatization conditions without requiring immediate side-chain protection. The hydrochloride salt form can improve handling and reproducibility during salt formation and derivative generation, which is relevant for process chemistry intermediate preparation. Enantiopure fractions obtained from such strategies can then be carried into protected amino acid synthesis, enantiomer-specific peptide coupling, and stereodefined peptidomimetic construction.
4. Chemical Biology Labeling
H-DL-Met-OEt · HCl can be used in chemical biology research contexts where methionine-like residues or methionine-derived fragments serve as handles for tagging, probe synthesis, or reactive group installation. The thioether side chain provides a chemically distinct motif that can be transformed into sulfoxide/sulfone or other sulfur-based functionalities, enabling orthogonal conjugation strategies to biomolecules or to solid-phase supports. The amino ester and salt state allow controlled progression from small-molecule labeling intermediates to amino acid derivatives compatible with peptide or linker incorporation. Downstream products can function as building blocks for biomolecule modification, enabling generation of labeled peptides, tracer conjugates, or mechanistic probes used in biochemical investigations.
5. Pharmaceutical Intermediate Preparation
H-DL-Met-OEt · HCl is relevant to pharmaceutical intermediate preparation and fine chemical synthesis where amino acid ester intermediates are required for controlled assembly of peptidic or peptidomimetic structures. The ester functionality supports conversion to activated carboxyl equivalents or to further protected derivatives aligned with C-terminal processing, while the amino hydrochloride state supports predictable handling during derivatization. The methionine thioether can be selectively oxidized to modulate physicochemical properties such as polarity and hydrogen-bonding capacity, which can be leveraged when designing sulfur-containing intermediates for medicinal chemistry programs. The compound's racemic nature also fits process development scenarios that evaluate synthetic routes prior to enantiopure selection, supporting downstream manufacturing intermediate generation for complex molecule construction.
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