H-Aib-OEt · HCl

H-Aib-OEt · HCl is the hydrochloride salt of the ethyl ester of alpha-aminoisobutyric acid (Aib), featuring an Aib backbone with a highly substituted alpha-carbon and a tertially substituted side-chain that restricts conformational freedom. The amino functionality is present as a protonated amine under HCl salt conditions, while the C-terminus is masked as an ethyl ester, enabling controlled peptide coupling and ester-based downstream transformations. The stereogenic center at the alpha-position can be used as a chiral building block, and the ester group participates in acylation and selective hydrolysis or transesterification strategies. The compound's salt form improves handling of the amino ester and supports its role as a protected or masked intermediate in peptide building-block preparation and synthetic organic chemistry.

1. Peptide Synthesis

H-Aib-OEt · HCl is applied in peptide synthesis workflows as an Aib amino acid ester building block where the ethyl ester can be converted into an activated carboxyl equivalent for coupling. The alpha-aminoisobutyric acid motif, with its sterically congested side-chain, supports incorporation of conformationally constrained residues that influence helix propensity in short peptides and peptidomimetics. The hydrochloride salt form helps manage the amino nucleophile during protection and activation steps, supporting reproducible peptide coupling chemistry. Downstream use includes preparation of Aib-containing peptide fragments and segment-based assembly for structure-activity relationship studies and conformational mapping.

2. Protected Amino Acid Chemistry

H-Aib-OEt · HCl is suitable for protected amino acid synthesis strategies because the amino group can be managed as a salt and the carboxyl functionality is already masked as an ethyl ester. The ester handle enables controlled conversion to acid derivatives, such as carboxylic acids or activated intermediates, while maintaining the Aib stereocenter for stereochemically defined peptide construction. Salt formation with HCl can be leveraged to tune nucleophilicity and facilitate orthogonal protection planning when preparing N-protected Aib derivatives. The resulting intermediates can serve as inputs for iterative synthesis of N-protected amino acids and for manufacturing routes that require consistent handling of amino ester substrates.

3. Peptidomimetics And SAR

H-Aib-OEt · HCl is used in peptidomimetic and medicinal chemistry research as a conformationally restricted residue precursor that can be incorporated into peptide analog scaffolds. The Aib side-chain substitution pattern and alpha-carbon stereochemistry can be used to modulate backbone torsional preferences, enabling systematic variation of peptide conformation in SAR studies. The ethyl ester functionality supports downstream transformations into amide-forming derivatives and facilitates building-block exchange during analog library synthesis. The compound therefore functions as a practical intermediate for generating Aib-containing molecular scaffolds used to probe sequence-dependent structure-function relationships.

4. Process Chemistry Intermediate

H-Aib-OEt · HCl is relevant to process chemistry intermediate preparation where amino acid ester substrates are required for scalable, reproducible downstream conversion into coupling-ready carboxyl forms. The hydrochloride salt improves solid-state handling and can support consistent feeding into synthetic sequences that involve ester hydrolysis, transesterification, or activation to carboxylic acid derivatives. The constrained Aib structure can reduce side reactions associated with less substituted amino acid backbones during controlled transformations, supporting robust intermediate manufacturing. The compound can be employed as a chiral amino acid intermediate in fine chemical synthesis for producing defined peptide building blocks and related constrained-residue derivatives.

5. Analytical Standards And Characterization

H-Aib-OEt · HCl can serve in analytical research and method development as a reference material for characterizing Aib-containing peptide intermediates and ester-to-acid conversion products. The defined amino ester structure, including the HCl salt form and ethyl ester group, provides distinct chromatographic and spectroscopic signatures for monitoring reaction progress and verifying identity of protected or activated derivatives. The stereogenic alpha-carbon and conformationally restricted Aib motif can aid in developing analytical methods that distinguish stereochemical variants or closely related amino acid derivatives. The resulting characterization support extends to quality control of peptide synthesis inputs and verification of intermediate formation in applied amino acid chemistry.

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