Umlagerungen von 6‐Bicyclo[3.2.1]octyl‐Kationen

Rearrangements of 6‐Bicyclo[3.2.l]octyl Cations 6‐Bicyclo[3.2.1]octyl cations were generated by nitrous acid deaminations of the amines 12, 14 and by acetolyses of the tosylates 9, 20 . the major products are bicyclo[3.2.1]octan‐ exo ‐6‐ol ( 17 ), bicyclo[3.2.1]octan‐ exo ‐2‐o. ( 18 ), and bicyclo[2.2.2]octan‐2‐ol ( 19 ). 4,6(4,5) hydride shifts account for the formation of 18 and 19 . The product distributions indicate substantial k S contributions for he endo precursors while the exo precursors react almost exclusively by way of carbocations, as confirmed by the ring expansion of bicyclo[4.1.1]octane‐2‐di‐azonium ions ( 30 . The product distributions obtained from the exo ‐diazonium ion 15n and from the exo ‐tosylate 20 are rather similar, but hte distributions of a deuterium label differ strongly. Dediazoniation of 15 leads to a highly unsymmetrical intermediate, whereas acetolysis of 20 involves an effectively equilibrated species. These findings cannot e interpreted in terns of open ions. Unsymmetrically bridged ions, whose conformational equilibration competes with substitution and hydride shifts, provide a consistent explanation.