N-BOC or N-FMOC benzaldimines are oxidized to the corresponding 3-Aryl-N-BOC or N-FMOC oxaziridines by reaction with Li m-chloroperoxybenzoate under aprotic conditions. The new oxaziridines can transfer their N-BOC or N-FMOC group to morpholine to give the corresponding N-beta-protected hydrazines.