Fmoc-[D4]Ala-OH

Fmoc-[D4]Ala-OH is a deuterium-labeled, Fmoc-protected alanine derivative in which the alpha carbon and/or closely associated positions bear four deuterium atoms, preserving the chiral alanine stereocenter while shifting NMR and mass spectrometric signatures. The molecule contains the Fmoc carbamate on the amino group and a free carboxylic acid, giving a protected amino acid ester/acid handle that participates cleanly in standard peptide coupling after Fmoc removal. The isotopic labeling enables quantitative tracing of alanine incorporation, peptide fragmentation, and metabolic or chemical transformation pathways with reduced spectral overlap. The combination of an acid functionality and a stable protecting group makes Fmoc-[D4]Ala-OH a chiral, isotope-resolved intermediate suited to peptide building block preparation and downstream analytical or synthetic studies.

1. Isotope Tracing Peptides

Fmoc-[D4]Ala-OH supports isotope-resolved peptide synthesis for chemical biology and analytical research where deuterium labeling enables tracking of alanine-containing segments in complex mixtures. The Fmoc-protected amine and free carboxylic acid allow incorporation as a defined residue during stepwise peptide coupling, while the D4 label provides predictable shifts in LC-MS and characteristic fragmentation patterns. Fmoc deprotection strategies can expose the reactive amine without disturbing the carboxyl group, enabling controlled assembly of labeled peptides for pathway mapping or mechanistic probing. Labeled products prepared from this amino acid can serve as internal standards, tracer peptides, or reference materials for studying residue-level transformations.

2. Protected Amino Acid Synthesis

Fmoc-[D4]Ala-OH is suitable for protected amino acid chemistry workflows that require a stable N-protecting group and a carboxylic acid for coupling chemistry. The Fmoc carbamate protects the amino functionality during storage and handling, while the stereochemically defined alanine backbone maintains consistent stereochemical outcomes in peptide bond formation. Deprotection of the Fmoc group can be applied to generate the reactive amine in situ for subsequent coupling steps, supporting reproducible synthesis of peptide building blocks and isotope-labeled analogs. The deuterium label further allows selective monitoring of synthetic intermediates and final peptides through mass-based readouts, which is useful for process development and method validation in fine chemical synthesis.

3. Peptide Coupling Compatibility

Fmoc-[D4]Ala-OH enables solid-phase or solution-phase peptide construction where compatibility with common peptide coupling reagents and standard protecting-group orthogonality is required. The free carboxylic acid and Fmoc-protected nitrogen align with established peptide coupling logic, supporting formation of amide bonds at the alanine residue while minimizing side reactions from unprotected amines. The D4 isotopic substitution can be leveraged to reduce ambiguity in residue assignment during MS/MS characterization of peptides and proteolytic digests. Peptide products incorporating Fmoc-[D4]Ala-OH can be used for sequence verification, labeling studies, and stereochemically consistent construction of labeled peptide standards.

4. Analytical Reference Standards

Fmoc-[D4]Ala-OH is applicable to analytical research and method development where isotopically labeled amino acids and peptides function as calibration tools and fragmentation references. The Fmoc-protected form and carboxylic acid functionality support preparation of defined labeled derivatives that can be quantified by LC-MS with improved selectivity due to the D4 mass shift. The labeled alanine residue can be incorporated into peptides that act as internal standards for quantifying alanine-containing motifs in complex matrices, including synthetic reaction mixtures and biological or chemical degradation samples. Downstream derivatization into peptide standards aligns with amino acid chemistry workflows that prioritize traceability and reproducible mass spectrometric behavior.

5. Pharmaceutical Intermediate Tracing

Fmoc-[D4]Ala-OH can be employed in pharmaceutical intermediate preparation and process chemistry studies where isotopic labeling is used to trace incorporation, monitor transformations, or support impurity characterization for peptide-like intermediates. The Fmoc-protected amino acid structure provides a controlled coupling handle for constructing labeled segments that can be followed through synthetic sequences using deuterium-resolved mass spectrometry. The stable carbamate protection and defined stereochemistry help maintain consistent chemical behavior during manufacturing-relevant steps, while the D4 label supports discrimination between closely related intermediates. Labeled peptides or amino acid-derived fragments generated from this building block can serve as traceable references for route scouting, analytical method qualification, and synthetic impurity profiling in specialty chemical production.

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