Fmoc-3,5-Difluoro-D-Phenylalanine

Fmoc-3,5-Difluoro-D-Phenylalanine is an Fmoc-protected D-phenylalanine derivative bearing two fluorine atoms on the aromatic ring at the 3,5-positions. The molecule combines a stereochemically defined chiral amino acid center with an activated N-terminus for base-mediated peptide coupling, while the difluorinated phenyl side chain modulates lipophilicity, metabolic stability, and hydrogen-bonding patterns through strong C-F effects. The aromatic fluorines are chemically persistent and can influence conformational preferences and binding-site complementarity in peptide and peptidomimetic scaffolds. The Fmoc carbamate and the D-configuration make it a controlled chiral building block for protected amino acid synthesis and downstream incorporation into sequences or functionalized intermediates.

1. Peptide Building Block

Fmoc-3,5-Difluoro-D-Phenylalanine is used in peptide synthesis workflows where Fmoc deprotection followed by amide bond formation enables stepwise construction of D-amino acid-containing peptides. The Fmoc-protected amine provides compatibility with standard coupling chemistries, while the carboxylate functionality allows formation of peptide bonds at the C-terminus during chain assembly. The D-configuration supports stereochemical control for generating defined backbone stereochemistry that can alter proteolytic stability and conformational behavior. The 3,5-difluorophenyl side chain can be incorporated to tune aromatic packing and molecular recognition in peptide libraries and sequence optimization studies, supporting robust downstream derivatization of the resulting peptide products.

2. Peptidomimetic SAR Studies

Fmoc-3,5-Difluoro-D-Phenylalanine is applied in SAR and molecular design programs for generating peptidomimetic analogs with controlled aromatic electronics and steric presentation. The difluorinated phenyl ring at the 3,5-positions introduces strong inductive and steric effects that can shift binding interactions without changing the overall amino acid topology. The D-amino acid stereocenter enables systematic evaluation of stereochemical hypotheses in structure-activity relationship studies, including backbone inversion effects and side-chain orientation changes. The Fmoc-protected form supports parallel synthesis of analog panels, enabling rapid access to difluoro-substituted peptide fragments and their subsequent functional group transformations for medicinal chemistry research.

3. Chemical Biology Labeling

Fmoc-3,5-D-Phenylalanine is suitable for chemical biology research where fluorinated aromatic residues serve as probes or handles within peptide and protein-modifying constructs. The protected amino acid framework allows incorporation into peptide tags using peptide coupling strategies, while the difluorophenyl side chain can participate in specific hydrophobic and polarizable interactions that may improve detectability in analytical readouts. The D-configuration can be leveraged to reduce enzymatic degradation of labeled peptides, supporting longer-lived tagging reagents in biochemical assays. Downstream, the Fmoc-derived peptide products can be further modified at termini or via additional functional groups introduced during synthesis, enabling biomolecule labeling workflows and mechanistic studies of molecular recognition.

4. Protected Amino Acid Synthesis

Fmoc-3,5-Difluoro-D-Phenylalanine is used as a chiral intermediate for protected amino acid chemistry and for preparing difluorinated phenylalanine derivatives with defined stereochemistry. The Fmoc carbamate provides an orthogonal protection strategy for the amino functionality, allowing controlled deprotection under base conditions while maintaining the integrity of the aromatic difluoro substituents. The carboxyl group enables conversion to alternative activated forms or coupling-ready derivatives during synthetic route design for fine chemical synthesis. The persistent C-F bonds support downstream transformations that rely on selective reactivity of other functional groups, making this building block compatible with manufacturing-scale planning for specialty amino acid derivatives and peptide-grade intermediates.

5. Pharmaceutical Intermediate Preparation

Fmoc-3,5-Difluoro-D-Phenylalanine is relevant to pharmaceutical intermediate preparation in the context of manufacturing peptide-based or peptidomimetic candidates and their synthetic intermediates. The Fmoc-protected amino acid format supports reproducible incorporation into larger fragments, aligning with industrially scalable solid-phase or solution-phase peptide construction concepts that require stable, isolable building blocks. The D-amino acid stereochemistry and difluorinated aromatic side chain can be carried through as a defined structural motif into drug discovery lead optimization, where consistent stereochemical identity is required across synthetic batches. The resulting peptide fragments and intermediates can then be directed toward further functionalization steps, including terminal modifications and conjugation-ready derivatives, supporting applied product development in chemical manufacturing settings.

6. Process Chemistry Intermediate

Fmoc-3,5-Difluoro-D-Phenylalanine is employed in process chemistry intermediate preparation where robust protection/deprotection behavior and chemical persistence of the difluorophenyl group support controlled route development. The Fmoc-protected amine and carboxyl functionality allow conversion into coupling-ready species, facilitating integration into manufacturing processes for protected amino acid synthesis and peptide building block preparation. The D-configuration supports stereochemically defined outputs, reducing ambiguity in downstream coupling and enabling consistent quality for difluorinated aromatic incorporation. The fluorinated aromatic side chain can also improve stability of intermediates under conditions that may otherwise affect less substituted aromatic systems, supporting reliable intermediate handling and subsequent synthetic elaboration into peptide analogs and specialty chemical products.

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