The Fries rearrangement reaction is an organic name reaction which involves the conversion of phenolic esters into hydroxyaryl ketones on heating in the presence of a catalyst. Suitable catalysts for this reaction are Brønsted or Lewis acids such as HF, AlCl3, BF3, TiCl4, or SnCl4. The Fries rearrangement reaction is an ortho, para-selective reaction, and is used in the preparation of acyl phenols.1 This organic reaction has been named after German chemist Karl Theophil Fries.
Figure 1.German Chemist Karl Theophil Fries
The photo-Fries rearrangement involves a similar conversion of phenolic esters into hydroxy ketones in the presence of UV light without catalyst.1
The thia-Fries rearrangement involves the conversion of aryl triflinates to trifluoromethanesulfinyl phenols in the presence of aluminum chloride in dichloromethane.2
The anionic phospho-Fries rearrangement involves the conversion of an aryl phosphate ester [ArOP(=O)(OR)2] into an ortho-hydroxyarylphosphonate [o-HO-Ar-P(=O)(OR)2]. This rearrangement yields phenols with an ortho C-P bond.3
The Fries rearrangement has found application in the following areas:
Figure 2.Para hydroxybenzophenone
Scheme of the above syntheses:
Figure 3.Oxa Michael Addition Reaction
Figure 5.Phenyl Acetate
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