Hafnium trifluoromethanesulfonate (Hf(OTf)4) as an efficient catalyst in the fries rearrangement and direct acylation of phenol and naphthol derivatives

Hafnium trifluoromethanesulfonate (hafnium triflate, Hf(OTf)4) was found to be an efficient catalyst in the Fries rearrangement of acyloxy benzene or naphthalene derivatives. The reactions proceeded smoothly in the presence of 5–20 mol% Hf(OTf)4. Regioselective direct acylation of phenol and naphthol derivatives with acid chlorides was also achieved by using Hf(OTf)4 as a catalyst.