L-allo-Threonine is a free, naturally occurring amino acid belonging to the threonine family, featuring a β-hydroxy side chain that differentiates it from serine by the presence of an additional methyl substituent. It contains an amino group and a carboxyl group on the α-carbon and bears a hydroxyl-functionalized, stereogenic side chain consistent with the "allo" stereochemical relationship implied by its name. As a threonine stereoisomeric building block, it is used in peptide synthesis and in amino acid analysis or structure-activity studies where stereochemical effects on incorporation, recognition, or derivatization are examined.
CAT No: CP01905
CAS No:28954-12-3
Synonyms/Alias:L-Allothreonine;L-allo-threonine;28954-12-3;L(+)-allo-Threonine;(2S,3S)-2-amino-3-hydroxybutanoicacid;allo-L-Threonine;DL-allo-Threonine;144-98-9;CHEBI:28718;EINECS249-327-2;MFCD00064268;(2S,3S)-2-amino-3-hydroxybutanoate;NSC206283;ALLO-THREONINE;BRN1721645;(2S,3S)-2-Amino-3-hydroxybutyricacid;rel-(2S,3S)-2-Amino-3-hydroxybutanoicacid;DL-allothreonine;Threonine,allo-;h-allo-thr-oh;Allo-Thr-OH;AmbotzHAA1188;l-(+)-allothreonine;4-04-00-03170(BeilsteinHandbookReference);AC1Q5QIO
L-allo-Threonine is an L-configured threonine stereoisomer featuring a chiral β-carbon bearing a side-chain hydroxyl group and a primary amino group paired with a carboxylic acid. The molecule's amino acid backbone supports standard peptide coupling chemistry at the α-amino and α-carboxyl functionalities, while the β-hydroxyl enables selective side-chain protection, derivatization, and controlled functional group transformations. The presence of a stereodefined side-chain alcohol introduces predictable reactivity under esterification, etherification, and oxidation conditions, making the compound a chiral amino acid intermediate for stereochemically defined products. L-allo-Threonine can be converted into protected amino acid derivatives that maintain stereochemical integrity through peptide synthesis and downstream synthetic steps.
1. Peptide Synthesis
L-allo-Threonine is employed as a peptide building block in peptide synthesis where the α-amino and α-carboxyl groups can be activated for amide bond formation. The β-hydroxyl side chain can be protected as an ether or ester to prevent side reactions during coupling and deprotection sequences, enabling clean incorporation into peptide sequences. Stereochemical definition at the α-carbon allows preparation of threonine analogs with defined configuration, supporting structure-activity relationship studies that distinguish allo- versus other threonine stereoisomers. The resulting protected amino acid derivatives can be used in stepwise solid-phase or solution-phase assembly to generate peptide fragments and longer peptide constructs with controlled side-chain functionality.
2. Side-Chain Functionalization
L-allo-Threonine is suitable for side-chain functionalization workflows that leverage the β-hydroxyl group for selective chemical modification. The alcohol can be transformed into esters, ethers, or activated intermediates for subsequent conjugation chemistry, including routes to hydroxyl-bearing peptidomimetics and modified amino acid residues. Protection-group strategies such as temporary β-O protection help maintain orthogonality relative to the α-amino and α-carboxyl during derivatization and later deprotection. Downstream, functionalized allo-threonine derivatives can serve as intermediates for generating bioactive peptide analog libraries and for producing stereochemically defined chemical probes.
3. Chiral Building Block Development
L-allo-Threonine functions as a chiral amino acid intermediate for the preparation of stereodefined fine chemicals and chiral auxiliaries where the allo stereochemistry is required. The combination of a primary amino group and a carboxylic acid enables conversion into N-protected amino acids and carboxyl-activated forms that participate in stereocontrolled coupling steps. The β-hydroxyl provides an additional stereosensitive handle that can be preserved, protected, or selectively oxidized/reduced to tune polarity and reactivity in downstream syntheses. The compound's defined stereochemistry supports construction of chiral scaffolds used in synthetic organic chemistry and in the manufacture of stereochemically consistent intermediates for research-grade molecular entities.
4. Chemical Biology Probes
L-allo-Threonine can be applied in chemical biology research to generate stereochemically defined peptide analogs and labeling reagents where threonine-like residues are needed with specific stereochemical identity. The α-amino acid functionality enables incorporation into peptides or peptidomimetics, while the β-hydroxyl supports conjugation handles after appropriate protection and activation. Orthogonal protection strategies allow selective functional group exposure for attaching tags, linkers, or reporter moieties without perturbing the peptide backbone chemistry. The resulting allo-threonine-containing constructs can be used as substrates, standards, or molecular probes to study recognition processes that depend on stereochemistry and side-chain geometry.
5. Pharmaceutical Intermediate Preparation
L-allo-Threonine is relevant to pharmaceutical intermediate preparation where amino acid-derived fragments are used to build peptidic or peptidomimetic motifs in synthetic pipelines. The amino acid backbone supports conversion into protected forms compatible with peptide coupling chemistry, while the β-hydroxyl can be managed through protection-group selection to align with manufacturing route constraints and purification needs. Stereochemical control at the α-carbon and preservation of the allo configuration can be important when downstream steps require defined stereochemical outcomes for structure-activity relationship studies. Protected allo-threonine derivatives and their functionalized analogs can therefore serve as process chemistry intermediates feeding into larger molecule assembly and analytical reference material generation.
6. Analytical Research Standards
L-allo-Threonine is used in analytical research contexts as a stereochemically defined reference material and derivatization substrate for amino acid profiling and method development. The presence of both an amino group and a carboxylic acid enables derivatization strategies that improve chromatographic or spectrometric detectability, while the β-hydroxyl can contribute to characteristic fragmentation patterns when converted into suitable derivatives. Allo stereochemistry supports discrimination from other threonine stereoisomers in chiral separation workflows and stereospecific quantification approaches. The compound's defined structure supports downstream preparation of analytical standards used to validate analytical methods for amino acid derivatives, peptide hydrolysates, and stereochemically sensitive synthetic intermediates.
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