H-p-Amino-D-Phe-OH · HCl

H-p-Amino-D-Phe-OH · HCl is a hydrochloride salt of an amino acid derivative featuring a D-configured phenylalanine backbone, with an additional para-amino substituent on the aromatic ring. The molecule contains an amino acid primary amine (as the salt-associated functionality), a carboxylic acid for peptide coupling, and a second aniline-type amino group that can participate in orthogonal protection and selective derivatization. The presence of the D stereocenter supports stereochemically defined incorporation into peptide sequences and stereochemical control during side-chain functionalization. Salt formation with HCl can influence solubility and handling during protected amino acid synthesis, while the free carboxyl group and aromatic amine enable downstream transformations such as amide formation, sulfonamide or urea construction, and selective coupling strategies after appropriate protection.

1. Peptide Synthesis

H-p-Amino-D-Phe-OH · HCl is used in peptide building workflows where a D-phenylalanine motif and a para-amino aromatic side chain enable incorporation of stereodefined residues into peptide chains. The carboxylic acid and amino functionality support peptide coupling chemistry after conversion to an activated acid or after installation of standard N-protection and C-activation compatible with peptide coupling reagents. The additional aniline group can be protected orthogonally to the amino acid amine to prevent side reactions during chain assembly, then deprotected for post-coupling modification or for generating amino-functional peptide analogs. The resulting D-configured peptidic scaffolds can be applied to peptide library construction, backbone stereochemistry studies, and the synthesis of amino-rich peptide conjugation handles.

2. Chemical Biology

H-p-Amino-D-Phe-OH · HCl serves as an amino acid-derived handle for chemical biology experiments that require controlled presentation of an aniline-type functionality on a stereodefined aromatic side chain. The para-amino group can be transformed into reactive electrophiles or linkable motifs through derivatization routes such as diazotization-compatible chemistry, sulfonamide formation, or urea/amide installation, while the amino acid carboxyl group supports attachment to biomolecular scaffolds via peptide bond formation. The D configuration can be leveraged to modulate proteolytic stability and to probe stereochemical effects on molecular recognition in labeled or modified biomolecule constructs. Downstream derivatives prepared from this scaffold can be used to generate functional probes, affinity tags, and chemically defined biomolecule conjugates for mechanistic studies.

3. Bioconjugation Chemistry

H-p-Amino-D-Phe-OH · HCl is applicable to bioconjugation workflows where the aromatic para-amino group functions as a conjugation handle and the amino acid framework provides a defined attachment point. The carboxylic acid enables formation of amide-linked intermediates that can be coupled to activated biomolecule carriers, while the ring amine can be protected during coupling and later converted into conjugation-ready groups for attachment to proteins, peptides, or polymer backbones. Salt-associated handling can support reproducible preparation of intermediates for conjugation chemistry, and the D stereocenter enables stereochemically defined incorporation into conjugate architectures. Prepared conjugation intermediates can be used to build labeled biomolecules, multivalent display constructs, and structurally characterized conjugates for analytical and research applications.

4. Protected Amino Acid Chemistry

H-p-Amino-D-Phe-OH · HCl is suitable as a chiral amino acid intermediate for protected amino acid synthesis, where orthogonal protection strategies are required to manage two distinct amine functionalities. The amino acid amine and the para-amino substituent can be protected independently to produce N-protected derivatives and side-chain-protected analogs that withstand peptide coupling conditions without undesired aromatic amine participation. The D stereochemistry is retained through protection and activation steps, supporting stereochemical fidelity in downstream peptide building block preparation. Resulting protected derivatives can be employed in solid-phase or solution-phase peptide synthesis, in fragment assembly for peptidomimetic construction, and as intermediates for systematic amino acid derivatization.

5. Process Chemistry Intermediate

H-p-Amino-D-Phe-OH · HCl can be employed as a process chemistry intermediate for fine chemical synthesis routes that require a stereodefined amino acid with an additional aromatic amine. The combination of a carboxylic acid for activation and an aniline-type amine for controlled derivatization supports manufacturing-friendly intermediate design, including conversion to activated esters or acid derivatives and subsequent selective functional group transformations after appropriate protection. The hydrochloride salt form can aid handling and reproducibility in intermediate preparation by improving crystallinity and aqueous compatibility during workup and purification steps. Downstream products derived from this intermediate can include amino-functional peptide analogs, functional aromatic amide/sulfonamide intermediates, and stereochemically defined building blocks for industrial-scale peptide and specialty chemical production.

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