Peptides containing the novel methylphosphinamide transition-state isostere

A convenient route towards the synthesis of peptides containing the methylphosphinamide moiety as a novel transition-state isostere of the amide bond hydrolysis is described. The key step being the coupling of a methylphosphinic chloride with an amino acid or peptide protected at the C-terminus. A proper choice of the amino protecting group appeared to be essential.