To a cooled solution (0 ºC) of the amino acid (193 mg, 1 mmol) and triethylamine (418 µL, 3 mmol) in CH2Cl2 (25 mL) was added POCl3 (460 mg, 3 mmol) dropwise, and the reaction mixture was stirred overnight at room temperature. The resulting solution was washed with saturated aqueous NaHCO3 (25 mL), brine (25 mL), and water (3 × 25 mL). Drying over anhydrous Na2SO4 and evaporation of the solvent yielded the β-lactam (145 mg, 83%).
Reference: Sharma, S. D.; Anand, R. D.; Kaur, G. Synth. Commun. 2004, 34, 1855–1862.
