Fries Rearrangement at Atmospheric Pressure Using Microwave Irradiation

The quest for odorants having salicylate notes

“…The main drawback is that the Fries rearrangement is usually not selective and leads, in the case where the para position of the phenol is unsubstituted, to a mixture of ortho and para products, even if authors have sometimes claimed good selectivities, depending on the conditions used (Scheme ). The ratio seems mainly dependent on the temperature, as well as on the nature and amount of Lewis acid used …”

“…[11][12][13][14][15][16][17][18][19][20][21] For rapid screening, we chose to use the two-step method via esterification of phenols followed by a Fries rearrangement. [22][23][24] This approach has several advantages. The two parts (phenols and acid chlorides) offer greater variability, are readily available and are inexpensive.…”

Submicron ZnO raspberries as effective catalysts for Fries rearrangement

“…For example, Paul and colleague 10 has shown that zinc powder efficiently catalyzes the selective Fries rearrangement of acetylated phenols under microwave heating or with conventional heating in the presence of N,N-dimethylformamide and in some cases, it was seen that different products were obtained using microwave heating and conventional heating. While the present state-of-the-art literature reveals that ZnO at the bulk or at the nanoscale has been employed as greener catalysts in Friedel-Cras acylation, Knoevenagel condensation, Biginelli reaction, Hantzsch condensation, phospha-Michael addition, Beckmann rearrangement and so on 14 and Fries rearrangement has been carried out using a wide variety of heterogeneous media or catalysts viz., scandium tri-uoromethanesulfonate, 15 sulfated zirconia, 16 zeolite, 17 electron beam irradiation within a cyclodextrin inclusion complex, 18 microwave irradiation, 19 ionic liquids, 20 etc. Belokon and group 12 reported TiCl 4 -catalysed Fries rearrangement via regioselective acylation of p-hydroxy [2.2] para-cyclophane to o-acylhydroxy [2.2] para-cyclophanes.…”

Sulfonylation reactions of aromatics using FeCl3-based ionic liquids

“…Our subsequent work [19][20][21][22][23][24] led to the extension of their use in different organic transformations. The low tolerance towards moisture in organoaluminates, necessitating the use of glove box and Schlenk techniques has hindered extensive progress in research.…”