Acyloxybenzene Fries rearrangements

Keywords acyloxybenzene, Fries rearrangement, microwave irradiation, flava-none, o-acyl phenol... 

The Fries rearrangement of acyloxybenzene or naphthalene derivatives proceeds smoothly in the presence of a catalytic amount of Sc(OTf)3 (Eq. 6) [19]. It has also been found that the triflate was an efficient catalyst in 2-acylation (direct acylation) reactions of phenol or naphthol derivatives with acid chlorides. Both reactions were successfully conducted by use of a small amount of Sc(OTf)3. 

Fries Rearrangement. Hf(OTf)4 was found to be an efficient catalyst in the Fries rearrangement of acyloxybenzene or the related 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 the catalyst (eq 32). ... 

Eshghi et al. (2003) reported Fries rearrangement of acyloxybenzene and naphthalene derivatives in presence of P O /SiO reagent under microwave heating in solvent-free media within 5 min. o-Hydroxyarylketones were obtained as products with moderate to excellent yields (47-98%). 

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