Ring expansion Wagner-Meerwein reactions

The low-temperature stability of bicyclo[2.2.1]heptane derivatives is well documented by the huge literature on liquid-phase norbornyl carbonium chemistry under such conditions, no ring expansion is observed, but instead, multiple Wagner-Meerwein rearrangements take place, preserving the bicyclo[2.2.1]heptane structure in the course of nucleophilic substitution or elimination reactions. This remarkable behavior is at the origin of the nonclassic carbonium ion concept (28). 

This reaction is related to the Wagner-Meerwein Rearrangement, Demjanov Rearrangement, Tiffeneau-Demjanov Ring Expansion and Retropinacol Rearrangement involving carbocation intermediates. 

Media s. Solvents Medium, superacidic reactions in - 27,159 Meerwein s. Wagner Meisenheimer rearrangement, ring expansion by - 26, 151 Meldmn s acids s. Malonic acid esters, cyclic Mercaptals... 

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