It can be applied in the synthesis of phosphopeptides. This derivative can be introduced using standard activation methods, such as PyBOP and TBTU. The monoprotected phosphoserine residue once incorporated is stable to piperidine. Using this reagent, even peptides containing multiple phosphorylation sites can be prepared efficiently by standard Fmoc SPPS methods. β-piperidinylalanine formation has been shown to occur during Fmoc deprotection of N-terminal Ser(PO(OBzl)OH), particularly under microwave conditions. This side reaction can be eliminated by using cyclohexylamine or DBU just for this Fmoc deprotection step .
