Dicationic Electrophiles from Olefinic Amines in Superacid

This paper describes the superacid-catalyzed chemistry of olefinic amines and related compounds. A variety of olefinic amines are found to react with benzene in CF3SO3H (triflic acid) to give addition products in good yields (75−99%), including the pharmaceutical agents fenpiprane and prozapine. A general mechanism is proposed that invokes the formation of reactive, dicationic electrophiles and the direct observation of a diprotonated species is reported from low-temperature NMR experiments. This chemistry is also used to conveniently prepare functionalized polystyrene beads having pendant amine groups.