Fmoc-OSu

Fmoc-OSu
N-(9-Fluorenylmethoxycarbonyloxy)succinimide (9-fluorenylmethyl N-succinimidyl carbonate)

The usual reagent for putting the Fmoc group on an amine. Amino acids react with it in water mixed with dioxane, acetone or acetonitrile, with sodium bicarbonate or carbonate as the base; other amines react in organic solvents with a tertiary base. The by-product, N-hydroxysuccinimide, washes out with water. It is less prone than Fmoc-Cl to forming Fmoc-dipeptide by-products, and it can protect hydroxy amino acids without first protecting the hydroxyl group.

A known side reaction: Fmoc-OSu can rearrange to give Fmoc-β-alanine, which turns up in the product as Fmoc-β-Ala-OH or as an Fmoc-β-Ala-amino acid dipeptide. Check new building blocks by HPLC before using them in SPPS.

Applications

• Fmoc protection of natural and unnatural amino acids for solid-phase peptide synthesis
• Fmoc protection of amines in organic and medicinal chemistry

Storage
Store refrigerated (2–8 °C) in a tightly closed container, and let it reach room temperature before opening.

References

1. Paquet A. Introduction of 9-fluorenylmethyloxycarbonyl, trichloroethoxycarbonyl, and benzyloxycarbonyl amine protecting groups into O-unprotected hydroxyamino acids using succinimidyl carbonates. Canadian Journal of Chemistry 1982, 60, 976–980. doi:10.1139/v82-146
2. Tessier M et al. Amino-acids condensations in the preparation of Nα-9-fluorenylmethyloxycarbonylamino-acids with 9-fluorenylmethylchloroformate. International Journal of Peptide and Protein Research 1983, 22, 125–128. doi:10.1111/j.1399-3011.1983.tb02076.x
3. Sigler GF et al. Formation of oligopeptides during the synthesis of 9-fluorenylmethyloxycarbonyl amino acid derivatives. Biopolymers 1983, 22, 2157–2162. doi:10.1002/bip.360221002
4. Obkircher M et al. Formation of Fmoc–β-alanine during Fmoc-protections with Fmoc–OSu. Journal of Peptide Science 2008, 14, 763–766. doi:10.1002/psc.1001
5. Hlebowicz E et al. Identification of Fmoc-β-Ala-OH and Fmoc-β-Ala-amino acid-OH as new impurities in Fmoc-protected amino acid derivatives. The Journal of Peptide Research 2005, 65, 90–97. doi:10.1111/j.1399-3011.2004.00201.x

For research use only. Not for human or veterinary use.