L-isoleucine tert.butyl ester hydrochloride is a derivatized amino acid in which L-isoleucine is converted to the tert-butyl ester, retaining the amino acid backbone while masking the carboxyl group as an O-tert-butyl ester and forming a hydrochloride salt at the amino functionality. The molecule therefore contains a protonated amino group (as the chloride salt) and an esterified carboxyl oxygen, with an isoleucine side chain bearing a branched aliphatic functionality that influences hydrophobic character and peptide-coupling behavior of the protected carboxyl equivalent. As an amino acid ester hydrochloride, it is used as a substrate or intermediate in chemical synthesis and peptide-related workflows where controlled handling of the carboxyl group is required, including preparation of further amino acid derivatives and stepwise assembly of peptide fragments.
CAT No: CP01228
CAS No:69320-89-4
Synonyms/Alias:69320-89-4;L-Isoleucinetert-ButylEsterHydrochloride;H-Ile-OtBu.HCl;L-Isoleucinet-butylesterhydrochloride;H-ILE-OTBUHCL;H-Ile-OtbuHydrochloride;119483-46-4;H-Ile-OtBu??HCl;KSC352S2F;SCHEMBL919003;L-Isoleucinet-butylesterHCl;CHEMBL1221960;CTK2F2922;IFRYMHOZFAPYPJ-WSZWBAFRSA-N;MolPort-000-150-589;ACN-S002362;ACT08609;ANW-35632;CI-039;MFCD00058015;AKOS015844546;AKOS015969123;AM81855;RL04649;RTR-023068
L-isoleucine tert.butyl ester hydrochloride is the hydrochloride salt of the tert-butyl ester of L-isoleucine, preserving the chiral α-amino acid stereocenter while converting the carboxyl group into a tert-butyl ester suitable for controlled activation and downstream transformations. The molecule contains a primary amino functionality as a salt (enhancing handling and solubility in polar media) and a side chain with a branched isopropyl group that supports hydrophobic peptide incorporation and stereochemically consistent residue behavior. The tert-butyl ester provides an acid-labile protecting-group strategy for temporary C-terminal masking during peptide coupling or multi-step synthesis, while the amino salt can be selectively liberated or used for coupling chemistry under standard peptide synthesis conditions. The resulting reactivity profile positions the compound as a chiral amino acid ester intermediate for peptide building block preparation, amino acid derivatization, and process-oriented fine chemical manufacturing routes.
1. Protected Amino Acid Ester
L-isoleucine tert.butyl ester hydrochloride is applied in protected amino acid ester chemistry for C-terminal masking during peptide building block preparation. The tert-butyl ester group can undergo acid-triggered deprotection to regenerate the carboxylic acid after coupling steps, while the L-configuration and branched isoleucine side chain maintain stereochemical fidelity in the final peptide or derivative. The amino hydrochloride form supports controlled liberation of the nucleophilic amine during synthetic sequence design, enabling compatibility with common peptide coupling strategies that require a defined amino/acid pairing. Downstream, the compound can serve as a chiral intermediate for generating free L-isoleucine, activated esters, or protected peptide fragments for iterative chain assembly in both research and manufacturing settings.
2. Peptide Synthesis Coupling
L-isoleucine tert.butyl ester hydrochloride is utilized in peptide synthesis workflows where an isoleucine residue must be introduced with a removable C-terminal ester protecting group. The protected carboxyl functionality participates as an ester-based intermediate that can be converted into coupling-ready forms, while the α-amino salt and preserved stereocenter support stereospecific incorporation into growing peptide chains. The tert-butyl ester strategy helps manage chemoselectivity by allowing sequential protection/deprotection planning across N- and C-terminal functional groups, reducing side reactions associated with unprotected carboxylic acids during multi-step assembly. Resulting peptide analogs and protected fragments can then be carried forward to generate longer sequences, test sequence-dependent properties, or prepare standards for analytical characterization.
3. Side-Chain Functionalization
L-isoleucine tert.butyl ester hydrochloride is relevant to amino acid derivatization programs focused on hydrophobic side-chain manipulation and downstream scaffold diversification. The branched isopropyl side chain provides a defined steric environment that can influence subsequent functionalization strategies, including transformations that introduce additional substituents on the residue while maintaining the α-chiral backbone. The tert-butyl ester allows temporary control of the carboxyl group during side-chain modification, so that functionalization can proceed without premature acid participation in undesired reactions. After side-chain elaboration, ester deprotection can enable conversion to peptide-compatible forms or further chiral intermediates for peptidomimetic construction and structure-activity relationship studies.
4. Chiral Intermediate Manufacturing
L-isoleucine tert.butyl ester hydrochloride is used as a chiral amino acid intermediate in process chemistry and specialty chemical production where stereochemical consistency is required across batch manufacturing. The combination of an L-stereocenter, a stable tert-butyl ester handle, and an amino hydrochloride salt form supports route design that separates protection, activation, and deprotection steps into controllable unit operations. The acid-labile tert-butyl ester can be integrated into manufacturing sequences to enable predictable generation of carboxylic acid functionality at specific stages, supporting downstream conversion to activated acids, mixed anhydrides, or peptide coupling reagents. The compound's role as a chiral building block precursor supports fine chemical synthesis of amino acid derivatives and peptide intermediates used in both research supply chains and industrial peptide manufacturing.
5. Analytical Standards And Labeling
L-isoleucine tert.butyl ester hydrochloride can be employed in analytical research and method development requiring chiral amino acid ester reference material. The defined stereochemistry and ester form help establish retention and derivatization behavior for chromatographic or mass spectrometric workflows that distinguish amino acid backbone states, such as esterified versus free acid forms. The hydrochloride salt form can improve reproducibility in sample preparation when comparing protected intermediates across synthetic sequences. Downstream, the compound can serve as a starting point for generating labeled or derivatized isoleucine-containing standards, supporting quality control of peptide building blocks, intermediate identity confirmation, and stereochemically consistent analytical reference generation.
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