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

Article abstract of DOI:10.1021/ol049512z

Matrix presented. In the Bronsted superacid CF₃SO ₃H (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 with benzene by Friedel-Crafts acylation.