Dicationic intermediates involving protonated amides: dual modes of reactivity including the acylation of arenes.

@article{Klumpp2004DicationicII,
  title={Dicationic intermediates involving protonated amides: dual modes of reactivity including the acylation of arenes.},
  author={Douglas A. Klumpp and Rendy Rendy and Yun Zhang and Alma Gomez and Aaron McElrea},
  journal={Organic letters},
  year={2004},
  volume={6 11},
  pages={
          1789-92
        }
}
In the Brønsted superacid CF(3)SO(3)H (triflic acid), amides are able to form reactive, dicationic electrophiles. It is shown that these dicationic intermediates participate in two distinctly different types of electrophilic reactions. The protonated amide increases the reactivity of an adjacent electrophilic group, and the protonated amide group itself shows enhanced reactivity arising from an adjacent cationic charge. In the latter case, several types of amides are even capable of reacting… 
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