Synthesis and reactions of exo-camphorylsulfonyloxaziridine

The first example of an exo-camphorylsulfonyloxaziridine 4a was prepared by m-CPBA oxidation of camphor imine 9. This surprising result is due to the conformation of the imine which apparently prevents attack of the peracid from the endo direction. Similar oxidations of all other camphorsulfonylimines result in the endo-oxaziridine exclusively. Asymmetric oxidation of sulfides to sulfoxides and the alpha-hydroxylation of enolates by 4 can be interpreted in terms of open transition states where nonbonded interactions are minimized. These results support earlier conclusions and predictions of the stereoselectivity and mechanisms of molecular recognition by the N-sulfonyloxaziridine class of oxidizing reagents.