A facile and effective synthesis of 2-azetidinones via phosphonitrilic chloride

The Staudinger reaction of imines to β-lactams was successfully achieved with substituted acetic acid and phosphonitrilic chloride in one-pot under mild conditions. Several types of β-lactams, especially 3-electron-withdrawing group β-lactams, can be synthesized by this versatile and efficient method in good to excellent yields. This method is simple, clean, and the by-products were removed by simple aqueous work-up. The effects of solvents, molar ratio of reagent, and the temperature were considered.