Fmoc-alpha-Me-D-Asp(tBu)-OH is an Fmoc-protected, non-proteinogenic amino acid derivative featuring a D-aspartic acid backbone bearing an alpha-methyl substitution (alpha-Me) and a tert-butyl ester-protected side-chain carboxyl group (Asp(tBu)). The molecule contains an N-terminal Fmoc carbamate that masks the amino group while the side-chain carboxyl is protected as a tert-butyl ester, with the free carboxyl group at the alpha position remaining available for coupling chemistry. In peptide synthesis workflows, it functions as a protected building block that supports stepwise incorporation of an alpha-methylated, D-configured aspartate analog into peptide chains and provides orthogonal protection patterns for controlled deprotection and subsequent derivatization.
CAT No: CP25240
CAS No:1231709-26-4
Synonyms/Alias:(R)-Fmoc-alpha-Methylaspartic acid-4-t-butyl ester
Chemical Name:(R)-N-alpha-(9-Fluorenylmethyloxycarbonyl)-C-alpha-methyl-aspartic acid beta-butyl ester (contains 10% MTBE)
Fmoc-alpha-Me-D-Asp(tBu)-OH is an Fmoc-protected, chiral D-aspartic acid derivative featuring an alpha-methyl substituent and a tert-butyl-protected side-chain carboxyl group. The molecule combines a stable carbamate-type N-protection for orthogonal peptide coupling with a masked side-chain acid that can be selectively deprotected to reveal a reactive Asp side chain. The D stereochemistry and the alpha-methyl stereocenter influence amide bond formation geometry and downstream conformational preferences in peptide and peptidomimetic scaffolds. The presence of both Fmoc and tert-butyl groups supports protection/deprotection workflows that are compatible with solid-phase and solution-phase peptide synthesis, while the carboxyl functionalities enable further derivatization and coupling chemistry.
1. Peptide Synthesis
Fmoc-alpha-Me-D-Asp(tBu)-OH is used as a protected amino acid building block for peptide coupling where the Fmoc group enables controlled N-terminal activation and subsequent removal during stepwise assembly. The alpha-methyl substitution and D-configuration allow incorporation of stereochemically defined residues that can modulate backbone sterics and local turn propensity in peptide sequences. The side-chain tert-butyl ester masks the aspartate carboxyl during chain elongation, reducing side reactions while preserving a latent functionality for later deprotection. Deprotected Asp side chains can then participate in intramolecular salt-bridge formation, crosslinking, or further functionalization, supporting peptide library construction and structure-activity relationship studies.
2. Peptidomimetics And SAR
Fmoc-alpha-Me-D-Asp(tBu)-OH supports peptidomimetic construction by providing a stereodefined, α-methylated Asp motif that can be incorporated into constrained analogs. The combination of N-Fmoc protection and a removable tBu side-chain protection enables synthesis of analog series where the Asp side chain remains available for carboxyl-based interactions after selective deprotection. D stereochemistry and the α-methyl center can be leveraged to tune conformational bias and binding-site complementarity in SAR workflows. Downstream transformations of the liberated side-chain carboxyl, such as conversion to amides, esters, or activated derivatives, facilitate generation of structure-diverse analogs for medicinal chemistry campaigns.
3. Chemical Biology Conjugation
Fmoc-alpha-Me-D-Asp(tBu)-OH can be applied in chemical biology to introduce a protected, stereochemically defined Asp side chain into peptide-based probes and conjugates. The orthogonal protection strategy allows selective unveiling of the side-chain carboxyl after peptide assembly, enabling conjugation handles for subsequent coupling to linkers, affinity tags, or imaging reagents. The α-methyl and D configuration can help stabilize probe conformations and reduce undesired proteolysis pathways associated with flexible residues. The resulting Asp-containing conjugates can be used to probe biomolecular recognition, map interaction interfaces, or build targeted chemical tools where precise stereochemistry matters.
4. Process Chemistry Intermediate
Fmoc-alpha-Me-D-Asp(tBu)-OH serves as a chiral intermediate for industrial fine chemical synthesis routes that require protected amino acid handling under scalable protection/deprotection logic. The Fmoc carbamate and tert-butyl side-chain protection provide robust functional-group masking during coupling chemistry, supporting manufacturing workflows that minimize side reactions from free amines or acids. The defined D stereochemistry and α-methyl substitution make it suitable for producing stereopure peptide building blocks and downstream amino acid derivatives used in larger-scale peptide or peptidomimetic manufacturing. The compound's protected carboxyl groups also enable controlled conversion to activated forms for further derivatization in process streams.
5. Analytical Standards
Fmoc-alpha-Me-D-Asp(tBu)-OH can be employed as an analytical reference material for method development and characterization of Asp-containing peptide fragments and protected amino acid intermediates. The distinct Fmoc and tBu protection patterns provide characteristic chromatographic and spectrometric signatures that support LC-MS and MS/MS identification of synthetic intermediates and deprotection endpoints. The α-methyl and D stereochemistry introduce stereospecific features that help validate stereochemical integrity during peptide synthesis and purification. Verified standards derived from this building block can support routine quality control of peptide coupling chemistry, protecting-group behavior, and identity confirmation in amino acid derivative workflows.
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