The intramolecular bromoamination of O-allyl-N-tosyl-hydroxylamines results in the formation of isoxazolidines via selective 5-endo-tet cyclization. This process occurs trans-selectively in high yield and diastereoselectivity. The obtained bromo-isoxazolidines provide access to other useful building blocks, such as 2-azido-aminoalcohols, diaminoalcohols, and aziridines.