Fmoc-Asn(Trt)-Wang Resin

Fmoc-Asn(Trt)-Wang Resin
Nα-Fmoc-Nγ-trityl-L-asparagine esterified to Wang (4-alkoxybenzyl alcohol) resin; 100–200 mesh, 0.3–0.8 mmol/g

Wang resin preloaded with Fmoc-Asn(Trt)-OH, for making peptide acids with a C-terminal asparagine by Fmoc SPPS. Remove the Fmoc group with 20% piperidine in DMF and build the chain as usual; final cleavage with 95% TFA and scavengers releases the peptide acid and removes the side-chain protecting groups. Include TIS to trap the trityl cation released from the side-chain amide. The loading for each lot is on its certificate of analysis.

The trityl group also keeps the side-chain amide from dehydrating to a nitrile during the couplings that follow. At the dipeptide stage the free amine can attack the ester bond to the resin and leave as a diketopiperazine. This is most likely when proline or glycine is one of the first two residues; couple the third residue promptly after the second Fmoc removal. 2-Chlorotrityl resin can reduce the loss for such sequences, though not eliminate it.

Applications

• Peptide acids with a C-terminal asparagine
• Glycopeptide work alongside glycosylated asparagine building blocks
• Manual and automated synthesis

Storage
Store refrigerated (2–8 °C) and dry, in a tightly closed container.

References

1. Wang S. p-Alkoxybenzyl Alcohol Resin and p-Alkoxybenzyloxycarbonylhydrazide Resin for Solid Phase Synthesis of Protected Peptide Fragments. Journal of the American Chemical Society 1973, 95, 1328–1333. doi:10.1021/ja00785a602
2. Sieber P et al. Protection of carboxamide functions by the trityl residue. Application to peptide synthesis. Tetrahedron Letters 1991, 32, 739–742. doi:10.1016/s0040-4039(00)74872-6
3. Pedroso E et al. Diketopiperazine formation in solid phase peptide synthesis using p-alkoxybenzyl ester resins and Fmoc-amino acids. Tetrahedron Letters 1986, 27, 743–746. doi:10.1016/s0040-4039(00)84089-7

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