Synthesis of Casein-Related Peptides and Phosphopeptides. V. The Efficient Global 'Phosphite-Triester' Phosphorylation of Protected Serine Derivatives and Peptides by Using Dibenzyl or Di-t-butyl N,N-Diethylphosphoramidite

Abstract

Both dibenzyl N,N- diethylphosphoramidite and di -t-butyl N,N- diethylphosphoramidite are shown to be suitable reagents for the efficient 1H-tetrazole-catalysed 'phosphite-triester' phosphorylation of the protected serine derivative Boc-Ser-OCH₂C₆H₄NO₂-p. Both these reagents were also used for the phosphorylation of the protected serine derivative Boc-Glu ( OBu^t )-Ser- Leu-OBu^t, and subsequent hydrogenolytic treatment of Boc-Glu ( OBu^t )-Ser(PO₃Bzl₂)- Leu-OBu_t or acidolytic treatment of Boc-Glu ( OBu^t )-Ser(PO₃Bu^t₂)- Leu-OBu^t gave the O- phosphoseryl tripeptide Glu -Ser(PO₃H₂)- Leu in near-quantitive yield.