REACTION OF OPTICALLY-ACTIVE EXO-2-BROMONORBORNANE AND ENDO-2-BROMONORBORNANE WITH NITRONIUM TETRAFLUOROBORATE IN ACETONITRILE - EVIDENCE FOR A CARBENIUM ION PATHWAY

Oxidation of both exo and encio-2-bromonorbornane with nitronium tetrafluoroborate in acetonitrile afforded N-exo-2-norbornylacetamide. Optically active exo-2-bromonorbornane afforded racemic acetamide, while 5% retention of optical activity was observed with the endo isomer. The data are consistent with a carbenium ion intermediate. A highly stereoselective conversion of optically active norcamphor to endo-2-bromonorbornane of known absolute configuration is described. Racemic endo-2-chloronorbornane has also been prepared. The 13C NMR spectra of the exo and endo-2-bromo-and-chloronorbornanes are compared to their corresponding alcohols. © 1979, American Chemical Society. All rights reserved.