An efficient method for the synthesis of sulbactam pivoxil.

Sulbactam pivoxil, a prodrug of the beta-lactamase inhibitor sulbactam, was prepared in high yield by reacting the sodium salt of sulbactam with chloromethyl pivalate in a polar solvent, then diluting the reaction mixture with water and isolating the product by filtration. Dimethyl sulfoxide was found to be the solvent of choice among several aprotic organic solvents.