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Fmoc-N-methyl-5-fluoro-L-tryptophan (Fmoc-N-Me-Trp(5-F)-OH) combines alpha-amino N-methylation with fluorination at the indole 5-position. This Fmoc-protected noncanonical tryptophan is used to introduce a backbone N-methyl residue and a position-defined aromatic fluorine in a single building block during peptide synthesis.
N-alpha methylation removes the backbone amide N-H after incorporation and can alter local hydrogen-bonding, conformation, and protease recognition. Ring fluorination provides a separate side-chain electronic variable. The two modifications should therefore be interpreted independently when designing SAR experiments.
Product Information
| Product Name | Fmoc-N-methyl-5-fluoro-L-tryptophan |
| Preferred Short Name | Fmoc-N-Me-Trp(5-F)-OH |
| Catalog No. | AS121 |
| Molecular Formula | C27H23FN2O4 |
| Molecular Weight | 458.49 g/mol |
| Stereochemistry | L |
| Modification | 5 |
| Primary Research Use | Fmoc-SPPS and noncanonical peptide SAR research |
Backbone N-Methylation and Ring Fluorination
This building block is not an indole-N-methyl tryptophan. The methyl group is associated with the alpha-amino nitrogen, while fluorine is located at indole position 5. That distinction matters for both chemical identity and the structural hypothesis being tested.
Other modified residues for conformational and side-chain studies can be explored in our unusual residue options.
Coupling Considerations for N-Methyl Residues
N-methyl amino acids are more sterically demanding during peptide-bond formation than their non-methylated counterparts. Coupling efficiency should be verified in the actual sequence, particularly when the next residue is also hindered or when resin-bound aggregation is present.
For projects containing multiple constrained residues, modified peptide projects can be planned around the complete sequence rather than a single coupling step.
Analytical and Design Checks
For procurement, confirm N-alpha methylation, fluorine position, L stereochemistry, formula, and CAS number where assigned. A vendor description that says only N-methyl fluorotryptophan does not fully define the material.
In SAR studies, a change observed with this residue reflects both backbone N-methylation and side-chain fluorination. Matched controls using non-methylated fluoro-tryptophan or N-methyl tryptophan can help separate those effects.
Product Documents
MSDS - Fmoc-N-methyl-5-fluoro-L-tryptophan (AS121)
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
Is the methyl group on the indole nitrogen?
No. In this product naming convention, N-methyl refers to N-alpha methylation at the amino-acid backbone nitrogen. The indole nitrogen remains distinct.
Why combine N-methylation with 5-fluorination?
The two changes probe different structural features: N-alpha methylation alters backbone hydrogen bonding and steric environment, while fluorination changes the indole side-chain electronic surface.
Are N-methyl residues coupled like standard Fmoc amino acids?
They can be incorporated by Fmoc-SPPS, but steric hindrance can make coupling more demanding. Sequence-specific monitoring and coupling optimization may be required.