Diastereoselectively Switchable Asymmetric Haloaminocyclization for the Synthesis of Cyclic Sulfamates

An asymmetric synthesis of cyclic sulfamates by catalytic haloaminocyclization of primary sulfamate ester derivatives is described. The remarkable reversal of diastereoselectivity was found to be dependent on the halogen source and the chiral catalyst. By using privileged complexes of N,N-dioxides with Sc(OTf)(3) or Lu(OTf)(3) as the catalyst, a variety of enantioenriched syn- and anti-cyclic sulfamates or related trans-aziridines could be obtained in 92-99% ee and up to 97% yield.