Dicationic electrophilic systems: the activation of carbocations and carboxonium ions by pyridinium groups and related heterocycles

N-Heterocycles can be alkylated with cinnamyl bromide to give the cationic salts 6–10 and subsequent reactions with C6H6 and superacidic CF3SO3H provide the addition products in good yields. Reactions of N-acetonylpyridinium salts give the condensation product from C6H6 and CF3SO3H and the dicationic intermediate can be directly observed using low temperature 13C NMR spectroscopy.