Simple and highly efficient synthesis of oxaziridines by tetrabutylammonium Oxone

Oxygenation of various aldimines with tetrabutylammonium monoperoxysulfate produced the corresponding E- or a mixture of E- and Z-oxaziridines with very high yields (?90%) and good to excellent selectivities (75-100%) within 20 min to 10 h in CH₃CN at room temperature (∼25 °C). The E/Z isomer ratio critically depends on the stereo-electronic nature of the substituents in the oxaziridines, solvent, and the presence of Lewis acids and bases.