Friedel–Crafts transformations are known for a long time and still present a very important class of chemical reactions.In terms of aryl-aryl couplings,the reaction is limited due to the thermodynamic instability of the phenyl cation.This fact gave rise to a large variety of coupling reactions using transition metal catalysts and activated arenes.Combining our groups knowledge about silylium ions in general[1] and our findings on carbon fluorine bond activation,[2] we developed a method for an intramolecular Friedel–Crafts type coupling of an aryl fluoride with an unactivated aryl nucleophile without using a transition metal.[3] The transformation involves cleavage of the C–F bond using the very reactive silylium ion and attack by an adjacent arene moiety within the same molecule.In our example reaction,we use an iPr3Si carborane initiator to abstract fluoride from 1-(2-Fluorophenyl)naphthalene,which is transformed to fluoranthene by ring closure and subsequent elimination of a proton.Since the proton can be used to generate a silyl cation from a silane,only a catalytic amount of initiator(i.e.silylium ion)is necessary.We applied this method to more complex systems to produce various polycyclic aromatic hydrocarbons.The scope was expanded to selected examples of nitrogen-containing substrates.Furthermore,the reaction pathway can be directed towards aliphatic C–H bond activation by placing a methyl group adjacent to the incipient phenyl cation(Scheme 1).The selectivity for either reaction depends on the strain of the ring to be formed and on the strength of the aliphatic C–H bond.This extended reactivity provides additional possibilities towards the synthesis of polycyclic aromatic hydrocarbons.