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Fmoc-2-(trifluoromethyl)-L-phenylalanine (Fmoc-Phe(2-CF3)-OH; CAS 352523-16-1) is an Fmoc-protected noncanonical L-phenylalanine bearing an ortho trifluoromethyl group. It is designed to introduce a position-defined CF3-substituted aromatic residue during Fmoc solid-phase peptide synthesis and peptide structure-activity studies.
The 2-CF3 substituent changes the steric, electronic, and lipophilic environment around the phenyl side chain without changing the peptide backbone itself. The effect on affinity, conformation, solubility, or biological activity is sequence-dependent, so this building block is best treated as a controlled SAR variable rather than as a universal performance-enhancing substitution.
Product Information
| Product Name | Fmoc-2-(trifluoromethyl)-L-phenylalanine |
| Preferred Short Name | Fmoc-Phe(2-CF3)-OH |
| Catalog No. | AS101 |
| CAS No. | 352523-16-1 |
| Molecular Formula | C25H20F3NO4 |
| Molecular Weight | 455.43 g/mol |
| Stereochemistry | L |
| Modification | 2 |
| Primary Research Use | Fmoc-SPPS and noncanonical peptide SAR research |
Why the 2-CF3 Position Matters
An ortho substituent sits close to the phenylalanine side-chain attachment point and can influence local aryl orientation and steric presentation differently from meta- or para-CF3 analogs. For medicinal-chemistry peptide work, exact substitution position is therefore part of the molecular identity, not a cosmetic naming detail.
Researchers comparing aromatic residue substitutions can review our aromatic amino acid series to select defined fluorinated and halogenated analogs.
Use in Fmoc-SPPS and SAR Design
The Fmoc-protected alpha-amino group is compatible with standard base-mediated Fmoc deprotection workflows. Coupling conditions should be selected for the complete sequence, especially when the modified aromatic residue is placed in a sterically crowded or aggregation-prone region.
For route-level considerations, the difficult SPPS planning provides context for coupling, deprotection, resin effects, and sequence-dependent synthesis behavior.
Analytical and Procurement Considerations
For procurement, confirm the exact 2-CF3 positional isomer, L stereochemistry, CAS number, purity specification, and lot-specific analytical documentation. Molecular weight alone cannot distinguish positional isomers or enantiomeric identity.
If stereochemical identity is critical, chromatographic purity should be interpreted together with chiral or other stereochemistry-supporting documentation where available. We consider this especially important when the product is used in comparative SAR studies against closely related fluoro- or CF3-substituted analogs.
Product Documents
MSDS - Fmoc-2-(trifluoromethyl)-L-phenylalanine (AS101)
The Safety Data Sheet provides product identification, hazard information, handling and storage guidance, exposure controls, transport information, and regulatory information for laboratory use.
Certificates of Analysis (COAs) are batch-specific. Please contact us to request the COA for your product, and we will provide it by email.
Frequently Asked Questions
What does Fmoc-Phe(2-CF3)-OH identify?
It identifies the Fmoc-protected L-configured amino-acid building block with the defined 2 aromatic substitution pattern.
Can a positional isomer be substituted if the molecular weight is the same?
No. Positional isomers are distinct chemical entities and can produce different peptide properties even when their formulas and nominal molecular weights are identical.
Does fluorination or halogenation guarantee better peptide activity?
No. These substitutions are controlled SAR variables. Their effects on affinity, conformation, solubility, stability, and activity depend on the complete peptide and assay context.