Phospho-serine and phospho-threonine building blocks for the synthesis of phosphorylated peptides by the Fmoc solid phase strategy

The synthesis of phospho-Ser and phospho-Thr-containing peptides based on Nα-Fmoc-O-(monobenzylphosphono)-Ser and -Thr building blocks is described. The building blocks were obtained by phosphorylation of the Fmoc-protected allyl ester derivatives following oxidation, removal of the allyl-group and selective cleavage of one phospho benzyl ester function with NaI.