O-Ethyl 1-azidoalkylphosphonic acids—versatile reagents for the synthesis of protected phosphonamidate peptides

A new methodology for the synthesis of protected phosphonamidate peptides from O-ethyl 1-azidoalkylphosphonic acids and amino acids esters was developed. The method is general and the corresponding N-Boc protected phosphonopeptides as well as their azido analogs have been obtained in good yields. An efficient preparation of O-ethyl 1-azidoalkylphosphonic acids is also presented.