Identification and suppression of β-elimination byproducts arising from the use of Fmoc-Ser(PO3Bzl,H)-OH in peptide synthesis

Abstract

The formation of 3-(1-piperidinyl)alanyl-containing peptides via phosphoryl β-elimination was identified from the application of Fmoc-Ser(PO 3Bzl,H)-OH in peptide synthesis as shown by RP-HPLC, ES-MS and 31P-NMR analysis. An N α -deprotection study using the model substrates, Fmoc-Xxx(PO3Bzl,H)-Val-Glu(O tBu)-Resin (Xxx = Ser, Thr or Tyr) demonstrated that piperidine-mediated phosphoryl β-elimination occurred in the N-terminal Ser(PO3Bzl,H) residue at a ratio of 7% to the target phosphopeptide, and that this side reaction did not occur in the corresponding Thr(PO 3Bzl,H)- or Tyr(PO3Bzl,H)- residues. The generation of 3-(1-piperidinyl)alanyl-peptides was also shown to be enhanced by the use o..