Rearrangements Fries-type

Attempts to isomerize the 2-methylene-3/f- azepine (45 R1 = H, R2 = PhCO) to the AT-benzoyl- 1H-azepine under acid- or base-catalyzed conditions failed. Irradiation of the 3//-azepine resulted only in a photo-Fries type rearrangement of the benzoyl group to give aminoketone (45 R1 = PhCO, R2 = H) (74JOC3076). 

The achievement of anionic ortho-Fries type rearrangements (320 324 and 325—>326) may open further DoM-based routes for the synthesis of oxygenated pyridines (Scheme 98) (85JOC5436). 

Besides oxygen, other nucleophiles have also been successfully employed as acceptors. For instance, N-, C-, S-, and / -glycosyl derivatives have been obtained from corresponding nucleophiles and O-glycosyl trichloroacetimidates in the presence of acid catalysts [1 ]. For instance, aryl-C-glycosjdes have been recently synthesized from phenols in an efficient Fries-type rearrangement reaction [37]. 

Hydroxythiocoumarins are, of course, enolic and react as acetoacetate analogues. Electrophiles such as Mannich reagents, aromatic aldehydes and enones react readily (Scheme 22), while acylation can be direct, or via a Fries-type rearrangement of 4-acyloxy precursors. 

Fries-type rearrangements (Sch. 15) (36) also occur photochemically this is generally a homolytic process, in contrast to the ionic mechanism of the thermal process. Azapropazone undergoes photoinduced 1,3-acyl shift in the solid state and fragmentation in solution (Sch. 16) (37). 

Iwasaki, S. (1976) Photochemistry of imidazolides. I. The photo-Fries-type rearrangement of N-substituted imidazoles. Helvetica Chimica Acta, 59 (8), 2738-2752. 

Tabuchi, H., Hamamoto, T., Ichihara, A. Modification of the Fries type rearrangement of the O-enol acyl group using W,W-dicyclohexylcarbodiimide and 4-dimethylaminopyridine. Synlett 1993, 651-652. 

Rearrangements.. Ary 1 sulfonates undergo Fries-type rearrangement when exposed to. MCl-.-ZnCI under microwave irradiation. ... 

Other N-substituted indoles have also been reported to undergo a photo-Fries type rearrangement of the substituent to other positions in the indole nucleus. The substituents that have been shown to migrate in this fashion include tosyl [34], alkoxy [34], aminocarbonylmethyl [38], and methoxycarbonylmethyl [38] (Scheme 6). 

The volatile products (which included a dimer) from the thermal degradation of poly (2,6-dimethyl-1,4-phenylene oxide) were analysed by gas chromatography-mass spectrometry. The primary breakdown route involved a Fries-type rearrangement of the polymer chain. The electron-induced fragmentation of the dimeric product has been studied in detail. ... 

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