In an effort to develop inhibitors of VanX, the phosphonamidate analogs of d-Ala-d-Ala dipeptides, N-[(1-aminoethyl) hydroxyphosphinyl]-glycine (1a),-alanine (1b),-valine (1c),- leucine (1d) and-phenylalanine (1e) were synthesized, characterized and evaluated using recombinant VanX. The crystal structure of the intermediate 6d was obtained (Deposition number: CCDC 839134), and structural analysis revealed that it is orthorhombic with a ...