Rearrangements in Carbonium Ion-Type Reactions of C¹⁴-Labeled Norbornyl Derivatives^1,2

Abstract

The extents of isotope-position rearrangement have been determined in solvolyses of exo- and endo-norbornyl-2,3-C_^(14) p-bromobenzenesulfonates and nitrous acid reactions of exo- and endo-norborny1-3-C^(14)amines. The bridged “norbornonium” ion proposed by Winstein and Trifan as the intermediate in cationic reactions of norbornyl derivatives does not suffice to account for the C^(14)-distributions in the reaction products. The formation of norbornyl derivatives with C^(14) in the 5-and 6-positions along with the observed percentages of rearrangement require 1,3-type hydride shifts which may occur by way of a “nortricyclonium” ion or its equivalent. The extent of rearrangement was found to increase in the solvolytic reactions as nucleophilic character of the solvent decreased. The rearrangement in the amine-nitrous acid reactions was relatively independent of solvent. More rearrangement was observed when the starting norbornyl derivatives had the exo-configuration. Possible interpretations of the experimental results are presented.