Fries Rearrangement

Abstract

Abstract The Lewis acid–promoted rearrangement of phenolic esters to ortho ‐ and/or para ‐acyl phenols is generally known as the Fries rearrangement. It has been reported that both Lewis acids and Brønsted acids work equally well for this reaction. A similar rearrangement also occurs on acyloxyheteroarenes (e.g., N ‐acetylcarbazole), and is known as Fries–Rosenmund rearrangement. It is found that arylsulfonates also undergo a similar rearrangement to afford hydroxyaryl sulfones, and such rearrangement is known as the thia‐Fries rearrangement. Comparable rearrangement of aryl esters under photo‐irradiation has also been developed. Similarly, the photo‐initiated rearrangement of aryl anilides to amino acyl aromatics is called the photo‐anilide rearrangement. The study finds that the presence of oxygen or the addition of pentasil zeolite, Nafion membrane or β‐cyclodextrin all affect the product distribution. This reaction has been used in the preparation of hydroxyl acyl phenols or heteroarenes (coumarin, carbazole, etc.)