Fries Rearrangement of Anilides in the Presence of Phosphorus Pentoxide in Methanesulfonic Acid

摘要

Aminoaryl ketones are an important class of compounds that exhibit a variety of interesting and useful properties. Some aminoaryl ketones are useful intermediates for the synthesis of benzodiazepines exhibiting activity as peptide antagonists, antivirals, antimalarials, and inhibitors of DNA interactions. Moreover, p-aminoaryl ketones are useful intermediates in the synthesis of other compounds that are used as sunscreens, anti-inflammatory agents, dyes, and inhibitors of MAP kinases. The Fries reaction of aryl esters is an important rearrangement in aromatic chemistry. In contrast to the widely studied Fries rearrangement of phenolic esters, relatively few papers have been reported on the Fries rearrangement of anilides to o- and p-aminoaryl ketones, by photolysis or thermolysis (above 200-350°C) with various Lewis acids such as ZnCl2, SnCl4, TiCl4, ThCl4 and BiCl3. The Fries rearrangement of acetanilide has been also reported over zeolite catalysts at 280°C with 50% conversion. Recently a Fries-type rearrangement of anilides has been reported by using strong bases via an anionic rearrangement.