Bisulfate Salt-Catalyzed Friedel–Crafts Benzylation of Arenes with Benzylic Alcohols

We report here a method of direct Friedel–Crafts benzylation of arenes with benzylic alcohols using cheap and readily available bisulfate salt as the catalyst in hexafluoroisopropanol. The catalytic system is powerful with a quite diverse group of functionalized arenes and benzylic alcohols. These mild conditions provide a straightforward synthesis of a variety of unsymmetrical diarylmethanes in high yield with good to high regioselectivity. An S_N1 mechanism involving activation of the hydroxy group through a hydrogen bond is proposed.