The regioselectivity of aziridine ringcleavage by nucleophiles (Cl−, Br−, I−, N3−, HBr) in a series of N-tosyl- and N-benzylepimino derivatives of 1,6-anhydro-β-D-hexopyranoses of D-allo, D-manno and D-galacto configurations has been studied. On treatment with halide anions, the tosylepimines 1, 3, 5 and 7 were opened trans-diaxially according to the Furst−Plattner rule. The courses of the reactions