H-Abu-OtBu·HCl

H-Abu-OtBu·HCl is the hydrochloride salt of tert-butyl-protected 2-aminobutyric acid (Abu) featuring an N-terminal amino group and a tert-butyl ester (OtBu) that masks the carboxyl functionality during synthesis. The salt form introduces a protonated amine (HCl) that improves handling of the chiral amino acid building block while maintaining reactivity for subsequent coupling steps after base-mediated neutralization. The molecule's stereogenic center and compact aliphatic side chain support incorporation into peptide-like sequences and side-chain constrained analogs, while the tert-butyl ester can be selectively deprotected under acid conditions to regenerate the free carboxylic acid. The overall structure functions as a chiral amino acid intermediate suitable for protected amino acid synthesis, downstream derivatization, and controlled peptide coupling chemistry.

1. Protected Amino Acid Synthesis

H-Abu-OtBu·HCl is used in protected amino acid synthesis workflows where a tert-butyl ester protects the carboxyl group while the amino functionality remains available for peptide coupling after salt neutralization. The OtBu ester strategy enables C-terminal carboxyl generation at a later stage, supporting stepwise assembly of peptide building blocks and minimizing side reactions from free acid during intermediate handling. The hydrochloride form can be leveraged to control amine protonation during storage and metering, then converted to the reactive nucleophile under coupling conditions. Downstream use commonly includes preparing activated carboxylic acid derivatives for fragment coupling and generating defined amino acid segments for synthetic peptide chemistry and process chemistry intermediate preparation.

2. Peptide Coupling Chemistry

H-Abu-OtBu·HCl serves as a short-chain amino acid building block for peptide coupling chemistry, particularly when an aliphatic Abu residue is required to tune backbone sterics and conformational preferences. The amino group participates in amide bond formation, while the tert-butyl ester protects the carboxyl terminus so that coupling can be directed to the intended N- or C-reactive site. Deprotection of the OtBu ester can provide a carboxylic acid handle for sequential elongation, enabling controlled N-to-C peptide construction and compatibility with standard peptide coupling strategies. The resulting Abu-containing peptide fragments can be applied in peptide science, peptidomimetic construction, and structure-activity relationship studies where side-chain length and stereochemistry influence molecular recognition.

3. Chiral Intermediate Manufacture

H-Abu-OtBu·HCl is suitable as a chiral amino acid intermediate in fine chemical synthesis and specialty chemical production where stereochemical integrity must be maintained through protection and deprotection steps. The presence of a single stereogenic center in the Abu framework supports downstream conversion into stereodefined derivatives, including activated acids, ester intermediates, and peptide-ready building blocks. The tert-butyl ester provides a robust protection handle for manufacturing route design, allowing isolation of protected forms and later conversion to the free acid for further functional transformations. Industrially, the compound can be employed in process chemistry intermediate preparation for producing defined stereochemical motifs used in peptide-based reagents, research-grade building blocks, and manufacturing of amino acid-derived specialty chemicals.

4. Amino Acid Derivatization

H-Abu-OtBu·HCl can be applied to amino acid derivatization strategies that exploit the protected carboxyl group and the protonatable amine to access multiple downstream functional forms. The OtBu ester can be converted to a free carboxylic acid to enable formation of amides, mixed anhydrides, or other carboxyl-activated intermediates, while the amine can be functionalized or protected to control chemoselectivity during multi-step synthesis. The aliphatic Abu side chain provides a platform for generating constrained analogs through further side-chain modification or incorporation into larger scaffolds. Derivatized products derived from this intermediate may serve as biochemical research intermediates, chemical biology probes, or synthetic precursors for peptidomimetics and SAR-focused molecular libraries.

5. Analytical Reference Standards

H-Abu-OtBu·HCl is applicable to analytical research as a stereodefined amino acid derivative standard and calibration component for method development involving amino acid ester and salt forms. The hydrochloride salt and tert-butyl ester create characteristic physicochemical behavior that can support chromatographic separation and detection method tuning for protected amino acids and related intermediates. Monitoring ester deprotection and salt neutralization can be performed using this compound as a reference for identifying OtBu-to-acid conversion endpoints in synthetic sequences. Analytical use extends to quality control of peptide building block preparation, characterization of intermediate mixtures, and verification of stereochemical retention in amino acid derivative synthesis.

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