Conversion of amino acids and dipeptides into their phosphonic analogs

Abstract Acylamino carboxylic acids were degradated by the Hunsdiecker-reaction; the bromo-derivatives were reacted with NaPO(OC2H5)2. Aminophosphonic acids were obtained by acidic hydrolysis, and half-blocked derivatives by the selective removal of masking substituents. Two phosphonopeptides [e.g. Alafosfalin (4i)] were also prepared by this route.