RING-OPENING OF (-)-CAMPHORSULFONIMIDE DERIVATIVES AND (-FENCHONESULFONIMIDE BY NITRONIUM TETRAFLUOROBORATE())

Treating a derivative of (-)-camphorsulfonimide (CA name: (3aS)-8,8-di methyl-4,5,6,7-tetrahydro-3 H-3 a,6-methano-2,1-benzisothiazole 2,2-di oxide) or the isomeric (+)-fenchonesulfonimide with nitronium tetraflu oroborate in acetonitrile does not lead to the expected products of ca tionic reactions, e.g. of the Ritter reaction for halogenated compound s, but provokes a cleavage of the sulfonimide group with the formation of a ring-opened product containing a sulfonyl fluoride and a nitroim ine group. The reaction does occur only in the presence of solid nitro nium tetrafluoroborate, but not after prior dissolution of the reagent . An X-ray structure of the product from (1 S)-3-endo-bromocamphorsulf onimide confirms this unusual reaction.