Preparation of phosphoamino acid derivatives with acid stable O-phosphono-protection for the Boc-mode solid-phase synthesis of phosphopeptides

Article abstract of DOI:10.1246/bcsj.68.2699

Boc-phosphoamino acid derivatives with O-[di(4-nitrobenzyl)- or dicyclohexylphosphono]-protection were prepared for application to the Boc-mode solid-phase synthesis of phosphopeptides. These protecting groups are both stable to TFA, but removable with a combination of trifluoromethanesulfonic acid and methylthiobenzene in TFA. Of these derivatives, N(α)-Boc-O-(dicyclohexylphosphono)serine and N(α)-Boc-O-(dicyclohexylphosphono)threonine were obtained as crystalline compounds to be favorably utilized as starting materials for solid-phase synthesis using an automated peptide synthesizer. On the other hand, N(α)-Boc-O-(dicyclohexylphosphono)tyrosine and all of the O-[di(4-nitrobenzyl)]phosphono derivatives were prepared as crystalline cyclohexylammonium or dicyclohexylammonium salts.