L-threonine tert.butyl ester hydrochloride is an amino acid ester derived from L-threonine in which the carboxyl group is converted to a tert-butyl ester while the amino functionality is present as a hydrochloride salt. The molecule retains the threonine side chain bearing a hydroxyl group, and the esterified carboxyl reduces the availability of the carboxylate for salt formation and peptide coupling chemistry relative to the free amino acid. As an esterified, salt-form amino acid derivative, it is used as a protected/activated building block for amino acid incorporation in peptide synthesis workflows and for preparing threonine-containing intermediates used in chemical biology and analytical method development.
CAT No: CP01937
CAS No:69320-90-7
Synonyms/Alias:69320-90-7;(2S,3R)-tert-Butyl2-amino-3-hydroxybutanoatehydrochloride;H-THR-OTBUHCL;L-Threoninetert-ButylEsterHydrochloride;H-Thr-OtBu.HCl;H-Thr-OtBu??HCl;threonine-t-butylester.HCl;C8H17NO3.HCl;SCHEMBL1825344;CTK5J1635;MolPort-009-680-853;OWBFRQWDQDYNNF-IBTYICNHSA-N;ANW-35633;KM1254;MFCD00672361;AKOS015847180;AM82245;CS15614;AK162700;KB-53408;L-threoninetert.butylesterhydrochloride;SC-09897;AB0072726;TR-023069;FT-0698850
L-threonine tert.butyl ester hydrochloride is an amino acid ester hydrochloride derived from L-threonine, featuring a chiral α-carbon that preserves the L-configuration and a β-hydroxy side chain capable of hydrogen bonding and selective derivatization. The tert-butyl ester masking group converts the carboxylic acid into a protected ester that can participate in peptide coupling workflows while remaining stable under conditions that would otherwise activate a free acid. The hydrochloride salt form protonates the amino functionality, improving handling and enabling controlled deprotection or neutralization strategies prior to coupling. The combination of an ester-protected carboxyl group and a stereogenic, hydroxyl-bearing side chain positions this compound as a practical intermediate for protected amino acid synthesis and downstream functionalization in peptide chemistry and synthetic organic chemistry.
1. Protected Amino Acid Synthesis
L-threonine tert.butyl ester hydrochloride is used in protected amino acid synthesis where a carboxylate-protected threonine scaffold is required for controlled peptide building block preparation. The tert-butyl ester provides a removable C-terminal protecting group, while the L-stereocenter and β-hydroxyl side chain enable stereochemically consistent incorporation into peptide sequences or further side-chain modification. Hydrochloride salt formation supports reproducible handling and can be managed to enable coupling-compatible free amine generation under standard peptide chemistry conditions. Downstream, the ester-protected intermediate can be converted into activated derivatives for amide bond formation and can serve as a biochemical research intermediate for threonine-containing analog construction.
2. Peptide Coupling Chemistry
L-threonine tert.butyl ester hydrochloride is applicable to peptide coupling chemistry as an amino acid ester hydrochloride that aligns with workflows for assembling threonine-containing peptides and peptide fragments. The protected carboxyl group and protonated amino functionality allow integration into coupling strategies that rely on temporary protection of reactive termini during stepwise synthesis. The β-hydroxyl side chain can be left protected or selectively transformed to tune chemoselectivity during sequential couplings, supporting preparation of peptides with defined side-chain functionality. Resulting threonine residues can be used in peptide building block preparation for synthetic peptide libraries, mechanistic studies, and structure-activity relationship investigations where side-chain hydrogen-bonding patterns matter.
3. Side-Chain Functionalization
L-threonine tert.butyl ester hydrochloride supports side-chain functionalization strategies that exploit the β-hydroxy group for derivatization into protected or reactive handles. The hydroxyl functionality can be converted into alternative protecting-group states or functional moieties to control reactivity during peptide synthesis and to enable orthogonal transformations after coupling. The preserved L-configuration ensures that stereochemical outcomes remain consistent when the modified threonine is incorporated into larger molecular frameworks. Downstream use includes preparation of functionalized threonine analogs for chemical biology research, including probes and constrained peptidomimetic fragments derived from stereodefined amino acid chemistry.
4. Chiral Building Block Development
L-threonine tert.butyl ester hydrochloride serves as a chiral amino acid intermediate for stereoselective synthesis of L-threonine-derived derivatives and fragment building blocks. The α-chiral center and β-hydroxy stereochemical environment provide a defined three-dimensional motif that can be carried through to downstream synthetic steps, including conversion of the ester into coupling-ready forms and controlled manipulation of the side-chain functionality. Hydrochloride salt handling can be leveraged to manage amine reactivity during intermediate preparation and purification in fine chemical synthesis. Resulting chiral intermediates can be applied to the construction of stereochemically defined peptidomimetics, amino acid-based scaffolds, and process chemistry intermediates that require reliable stereochemical fidelity.
5. Pharmaceutical Intermediate Preparation
L-threonine tert.butyl ester hydrochloride is suitable for pharmaceutical intermediate preparation where protected amino acid derivatives are needed for manufacturing routes to peptide-like or peptidomimetic compounds. The tert-butyl ester masking group functions as a C-terminal protection strategy that can be designed to withstand upstream transformations and then be removed to reveal a carboxylic acid for subsequent coupling or further functional group interconversions. The β-hydroxyl side chain enables generation of protected variants that can be carried through multi-step syntheses while maintaining chemoselectivity for later stages. Downstream, the material can be employed as a process chemistry intermediate for constructing threonine-containing intermediates used in specialty chemical production and applied synthetic organic chemistry.
6. Analytical Research Standards
L-threonine tert.butyl ester hydrochloride can be used in analytical research as a stereochemically defined threonine derivative standard for method development and impurity profiling in amino acid and peptide analyses. The presence of a protected ester and a β-hydroxy side chain provides chromatographic and derivatization behavior distinct from free threonine, supporting discrimination of esterified species and related intermediates. Hydrochloride salt formation improves reproducibility in sample preparation for analytical workflows that require consistent salt forms or controlled ionization states. Downstream, the compound can serve as a reference material for verifying identity and monitoring conversion of protected amino acid intermediates during peptide building block preparation and industrial chemical manufacturing steps.
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