Bromination and chlorination of exo,exo-5,6- and endo,endo-5,6- dideuterionorbornene; on the mechanism of nortricyclyl bromide and chloride formation

Proton (deuteron) loss from C-6 to form tricyclic product occurs with exo and endo stereoselectivity when bromine and chlorine, respectively, are added to exo,exo-5,6- and endo,endo-5,6-dideuterio-norbornene. These data strongly suggest that elimination occurs predominately from 6 in bromination and from 4 in chlorination or alternatively from the unsymmetrically bridged ions 2 and 3, respectively.