A series of amidoketophosph (on) ates of general structure PhCH2OCONHCH (R) COCHR'(CH2) n (O) P (O2-)(O) R''(R= H, CH3; R'= H, CH3; n= 0, 1; R''= H, CH3, Et, Ph) have been prepared as a potential source of β-lactamase inhibitors. The phosphonates (n= 0)