Friedel-Crafts Reaction of Benzyl Fluorides: Selective Activation of CF Bonds as Enabled by Hydrogen Bonding

A Friedel–Crafts benzylation of arenes with benzyl fluorides has been developed. The reaction produces 1,1‐diaryl alkanes in good yield under mild conditions without the need for a transition metal or a strong Lewis acid. A mechanism involving activation of the CF bond through hydrogen bonding is proposed. This mode of activation enables the selective reaction of benzylic CF bonds in the presence of other benzylic leaving groups. Be selective! A Friedel–Crafts benzylation of arenes with benzyl fluorides (see example; HFIP=1,1,1,3,3,3‐hexafluoro‐2‐propanol) is proposed to proceed by a mechanism involving activation of the CF bond through hydrogen bonding. This mode of activation enables the selective reaction of benzylic CF bonds in the presence of other benzylic leaving groups.