Chemistry of oxaziridines. 18. Synthesis and enantioselective oxidations of the [(8,8-dihalocamphoryl)sulfonyl]oxaziridines

The synthesis and enantioselective oxidations of [(8,8-dihalocamphoryl)sulfonyl]oxaziridines [8,8-dichloro-1,7,7-trimethyl-2'-(phenylsulfonyl)spiro[bicyclo[2.2.1]heptane-2,3'-oxinidine]] 13 are reported. These reagents are prepared in two steps from the (camphoxylsulfonyl)imine 4 by treatment of the corresponding azaenolate with electrophilic halogen sources followed by biphasic oxidation of the resulting dihalo imine 6-9 with m-CPBA/K 2 CO 3 . Of these oxaziridines the dichloro reagent 13b, available on a multigram scale, affords the highest enantioselectivities for the asymmetric oxidation of sulfides to sulfoxydes (42-74%) and for the hydroxylation of enolates (often better than 95% ee).