Thermodynamic control Fries rearrangement

Reaction of phenol derivatives with acyl chlorides in acidic conditions may result in O-acylation or C-acylation, either directly or via a Fries rearrangement. Studies of acylations in acetonitrile using trifluoromethanesulfonic acid (trifllc acid) have shown that O-acylation is favoured at a low acid concentration, while a high acid concentration favours C-acylation. It has also been shown that A-hydroxysuccinimidyl and phenyl esters of benzoic acids are activated by triflic acid and can be used to acylate electron-rich arenes such as ferrocene or pyrene the reactive acylating intermediate is likely to be an acyl triflate or its protonated form. In a polyphosphoric acid medium, the rearrangement of 1,5- 1,8- and 9,10-diacetylanthracenes leads to the formation of the ring-closed product (56). DFT calculations support the conclusion that the reaction involves the intermediacy of 1,9-diacetylanthracene formed under kinetic rather than under thermodynamic control. ... 

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See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ , ]

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