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N-Fmoc-n'-methyl-l-Asparagine (CAS 149204-93-3) is supplied as an Fmoc-protected N4-methyl-L-asparagine building block. In research synthesis, it is most relevant to side-chain N-methyl asparagine analog and modified-peptide synthesis and site-defined asparagine side-chain amide methylation and amide-structure SAR.
The methyl group is on the asparagine side-chain amide, not on the peptide backbone nitrogen; treat it as a permanent side-chain modification. Before substitution into an established synthesis, compare stereochemistry, protecting-group orthogonality and downstream deprotection requirements.
Product Information
| Product Name | N-Fmoc-n'-methyl-l-Asparagine |
| Catalog No. | AS4224 |
| CAS No. | 149204-93-3 |
| Molecular Formula | C20H20N2O5 |
| Molecular Weight | 368.38 g/mol |
| Compound Type | Fmoc-protected N4-methyl-L-asparagine building block |
| Primary Research Use | Side-chain N-methyl asparagine analog and modified-peptide synthesis |
Side-Chain N-Methyl Asparagine Chemistry
N-Fmoc-n'-methyl-l-Asparagine contains an Fmoc-protected alpha amino group and an N4-methylated asparagine side-chain amide. The methyl group therefore changes the side-chain amide itself rather than creating a backbone N-methyl residue.
Use in Modified-Asparagine Peptides
This building block can be used when a peptide or peptidomimetic design requires a site-defined N-methyl asparagine side chain for amide-structure, hydrogen-bonding or SAR studies. It should be compared with ordinary Asn and side-chain-protected Asn derivatives as a distinct residue identity.
Coupling and Final Structure
Fmoc chemistry controls the alpha amino group during assembly, while the N4-methyl substituent is intended to remain in the final side chain. Sequence calculations and analytical assignments should therefore use the modified residue rather than native asparagine.
Additional chemistry is available in the specialty amino acid set. For synthesis planning beyond the building block, see specialty SPPS building blocks.
Product Documents
MSDS - N-Fmoc-n'-methyl-l-Asparagine (AS4224)
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
Where is the methyl group in this asparagine derivative?
It is on the asparagine side-chain amide nitrogen (N4), not on the peptide backbone nitrogen.
Does the side-chain methyl group remain in the final peptide?
Yes. It is part of the designed residue identity rather than a temporary protecting group.
Why distinguish this from an N-methyl backbone residue?
Backbone N-methylation changes the peptide amide directly, whereas N4-methyl asparagine modifies the side-chain amide and has a different structural effect.