Regio- and stereo-controlled opening of 2,3-epoxy amines and 2,3-aziridine amines by the commercially available MgBr2 is described. As reported, this new method could represent a general and useful approach for the preparation of promising intermediates. Moreover, in particular cases, the reaction evolves toward an interesting oxazolidin-2-one structure. J. Heterocyclic Chem., (2010).