The synthesis of phosphopeptides via the Bpoc-based approach

Abstract

The 2-(p-biphenylyl)-2-propyloxycarbonyl (Bpoc) group was examined as an N^α-protecting group in the stepwise assembly of the MAP Kinase ERK2 [178–188; Thr(P)¹⁸³, Tyr(P)¹⁸⁵] peptide. The mild acid deprotection of the Bpoc group permitted (i) incorporation of a fully protected phosphothreonyl derivative and (ii) a TFA-based final cleavage step. The first five C-terminal residues (184–188) were incorporated in the Fmoc mode of peptide synthesis, with all subsequent amino acids coupled as their Bpoc–Xxx–OH derivatives. The target product was obtained in high purity and yield, indicating that a Bpoc-based approach to phosphopeptide synthesis was compatible with both the acid-labile side chain protecting groups employed and Hmp–Wang resin.