BRIDGED POLYCYCLIC COMPOUNDS .59. STEREOCHEMISTRY OF REARRANGEMENTS IN DIBENZOBICYCLO[2.2.2]OCTADIENYL AND DIBENZOBICYCLO[3.2.1]OCTADIENYL SYSTEMS AND OF ADDITIONS TO DIBENZOBICYCLO[2.2.2]OCTATRIENE

cis-3-Deuteriodibenzo-2-bicyclo[2.2.2]octadienyl p-toluenesulfonate (6) is converted stereospecifically upon acetolysis into syn-8-deuteriodibenzo-exo-2-bicyclo[3.2.1]octadienyl acetate (7). In perchloric acid-acetic acid this exo acetate is rapidly transformed to an equilibrium mixture with its endo epimer and is then stereospecifically rearranged to cis-3-deuteriodibenzo-2-bicyclo[2.2.2]octadienyl acetate (8). The results are discussed in terms of a single classical cationic intermediate (12). Addition of acetic acid to dibenzobicyclo[2.2.2]octatriene (3) gives dibenzo-2-bicyclo[2.2.2]octadienyl acetate (11). This reaction is substantially slower than the rearrangement of either endo- or exo-dibenzo-2-bicyclo[3.2.1]octadienyl acetates (9 and 10) to dibenzo-2-bicyclo[2.2.2]- octadienyl acetate (11), so that their intermediacy cannot be ascertained. Addition of deuterioacetic acid leads to both cis- and trans-3-deuteriodibenzobicyclo[2.2.2]octadienyl acetates (8 and IS), but most (and perhaps all) of the trans product arises from acid-catalyzed isomerization of the cfs-addition product 8. Similar results obtain with trifluoroacetic acid and deuteriotrifluoroacetic acid. © 1969, American Chemical Society. All rights reserved.