H-D-Asp(tBu)-OtBu*HCl

H-D-Asp(tBu)-OtBu*HCl is a protected D-aspartic acid derivative in which the α-amino group is in the N-acetylated (H-D-Asp) form and the side-chain carboxylic acid is masked as a tert-butyl ester (Asp(tBu)), while the α-carboxyl group is also present as a tert-butyl ester (OtBu) and the material is provided as a hydrochloride salt. The molecule therefore bears two tert-butyl-protected carboxyl functionalities and a defined D-stereocenter at the amino acid backbone, creating a controlled, acid-stable platform for peptide coupling and orthogonal deprotection planning. The tert-butyl ester groups can be removed under standard acidolysis conditions to regenerate aspartate carboxylates, enabling downstream formation of amide bonds, side-chain carboxyl activation, and selective derivatization. The salt form improves handling of the protected amino acid intermediate in synthetic workflows where amine protonation state influences coupling efficiency and purification behavior.

1. Peptide Synthesis

H-D-Asp(tBu)-OtBu*HCl supports peptide building block preparation for solid-phase or solution-phase assembly where aspartate residues must be introduced with side-chain carboxyl protection. The protected α-carboxyl (OtBu) and side-chain carboxyl (Asp(tBu)) reduce competing acylation and suppress uncontrolled crosslinking during coupling, while the D-configuration provides stereochemical control for D-Asp-containing peptides and D-amino acid rich sequences. The N-acetylated amino functionality and hydrochloride salt state can be leveraged to manage reactivity during activation and coupling steps, aligning with protected amino acid synthesis strategies. Acid-mediated deprotection can unmask both carboxyl groups for subsequent peptide elongation logic or for generating defined functional peptide termini and side-chain modifications.

2. Amino Acid Side-Chain Functionalization

H-D-Asp(tBu)-OtBu*HCl is suitable for side-chain functionalization workflows that require controlled access to aspartate carboxylates after orthogonal deprotection. The tert-butyl-protected side-chain carboxyl (Asp(tBu)) enables selective conversion to activated carboxyl derivatives, amide-forming intermediates, or ester/amide-linked handles used in chemical biology and materials chemistry. The D-aspartate stereochemistry can be used to tune conformational preferences and binding-site compatibility in peptidomimetic scaffolds where stereochemical inversion relative to L-aspartate changes recognition. The resulting functionalized aspartate derivatives can serve as downstream intermediates for fragment elaboration, linker installation, or incorporation into larger conjugation targets.

3. Peptidomimetics And SAR Studies

H-D-Asp(tBu)-OtBu*HCl can be applied to peptidomimetic construction and structure-activity relationship studies by enabling systematic variation of D-aspartate-containing motifs. The dual tert-butyl ester protection pattern preserves both carboxyl groups during scaffold assembly, supporting consistent synthetic comparison across analog series while minimizing side reactions that complicate SAR interpretation. The defined D-stereocenter at the backbone allows stereochemical mapping of how inversion affects local charge distribution and hydrogen-bonding geometry in bioactive conformations. Deprotection and subsequent derivatization can generate analogs with carboxylates available for salt-bridge formation, metal coordination studies, or controlled acidity tuning within molecular design campaigns.

4. Protected Amino Acid Chemistry

H-D-Asp(tBu)-OtBu*HCl functions as a chiral, protected amino acid intermediate for process chemistry intermediate preparation and protected amino acid synthesis planning. The tert-butyl ester groups provide a predictable protection strategy for carboxyl functionality, supporting manufacturing-relevant workflows that rely on robust protection during activation, coupling, and purification. The hydrochloride salt form stabilizes the amine handling state and can influence downstream activation chemistry, while the N-acetylated form helps define the amide-forming behavior during peptide coupling sequences. Acidolysis-compatible deprotection allows conversion to D-aspartate carboxylate-bearing intermediates used for further functional group transformations, including activation to carboxylic acid derivatives and controlled re-protection for sequential synthesis steps.

5. Bioconjugation Linker Synthesis

H-D-Asp(tBu)-OtBu*HCl is applicable to bioconjugation chemistry where aspartate-derived linkers require protected carboxyl groups during synthetic assembly. The protected α- and side-chain carboxyl groups can be unmasked to generate carboxylate handles for coupling to electrophilic conjugation partners, including activated esters or amide-forming reagents used to attach biomolecule-reactive moieties. The D-aspartate configuration can be used to modulate linker stability and local stereoelectronic effects, which may influence conjugate behavior in analytical and biochemical research contexts. The compound thus serves as a practical amino acid-based intermediate for producing defined linker architectures that integrate into peptide conjugates, protein labeling reagents, or other biomolecule modification constructs.

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