Synthesis of Peptide Analogues Containing (2-Aminoethyl)phosphonic Acid (Ciliatine)
Di- and tripeptide analogues containing (2-aminoethyl)phosphonic acid , which has been discovered in a wide variety of living organisms, were prepared.As starting materials for incorporating the amino phosphonic acid into a peptide chain, the N-phthalylated diethyl ester and the N-carbobenzyloxylated monoalkyl ester were used.A phosphonamide bond between the amino phosphonic acid unit and amino acid unit was formed by reaction of Pht-Aep(OEt)Cl with amino acid ethyl ester or coupling reaction between Cbz-Aep(OR)(OH) and amino acid ethyl ester using diphenylphosphoryl azide-triethylamine as a condensing agent.Removal of the protecting groups was studied in connection with the acid-labile phosphonamide bond in the abnormal peptides.