Photo-Fries Rearrangement

The photo‐initiated rearrangement of phenyl or aryl esters is generally known as the photo‐Fries rearrangement or photo‐Fries reaction and usually carried out in an aprotic solvent. This reaction is affected by electronic nature of substrate as well as the reaction environment and no apparent isotopic effect has been observed. All the mechanistic features of this rearrangement have been discussed and compared with the normal Fries rearrangement catalyzed by Lewis acid. The study finds that regioselectivity can be further enhanced when the photo‐Fries rearrangement is carried out in presence of zeolite. Besides phenyl and aryl esters, several other kinds of compounds can also undergo the hemolytic cleavage from photo‐irradiation. This reaction is not useful in actual organic synthesis because of its different by‐products.