Synthesis of a series of new alkyl -2-[5-(hydroxyl methyl)-5-nitro-2-oxo-1, 3, 2 λ 5 - dioxaphosphinan-2-yl] amino acid esters ( 5a-j ) was accomplished through a two-step process. The key step in the synthesis of 5a-j involves preparation of a dichloride intermediate ( 3a-j ), with different aminoacid esters and with a few substitut ed phenols by reacting POCl 3 in presence of Et 3 N in THF at 0-15 o C. In the second step the intermediate in situ is t reated with tris (hydroxyl methyl) nitromethane (2-hydroxy methyl-2-nitro-1, 3 -propanediol) ( 4 ) in the presence of Et 3 N at 40-45 o C to form 5a-j . The structures of 5a-j were established by elemental analysis, IR, 1 H, 13 C and 31 P NMR and mass spectral data. The antimicrobial act ivity of these compounds was evaluated and they exhibited moderate antifungal an d anti bacterial activities.