Preparation of phosphopeptide thioesters by Fmoc- and Fmoc(2-F)-solid phase synthesis

Efficient methods for the preparation of phosphopeptidethioesters were examined, using Fmoc-based solid-phase method.Phosphopeptide thioesters were obtained in good yields by theuse of 1-methylpyrrolidine, hexamethyleneimine and 1-hydroxybenzotriazole in a DMSO-DMF (1:1, v/v) solution fordeblocking the Fmoc groups. Epimerization, which is oftenobserved at the C-terminal amino acid, was effectivelysuppressed by shortening the time of deblocking process viathe use of highly base sensitive Fmoc(2-F) groups for -aminoprotection.