Phenyl benzoates Fries rearrangement

Phenylalanylglycine, synthesis of, 1077-1081 Phenyl benzoate, Fries rearrangement of, 952 2-Phenyl-2-butanol p-nitrobenzoate, 595 preparation of, 559 Phenylbutazone, 856 2-Phenylethanol... 

Banks, M. R. Fries rearrangement of some 3-acetoxy- and 3-(propionyloxy)thiophenes. J. Chem. Soc., Perkin Trans. 11986, 507-513. Dawson, I. M., Gibson, J. L., Hart, L. S., Waddington, C. R. Aromatic rearrangements in the benzene series. Part 5. The Fries rearrangement of phenyl benzoate the rearranging species. The effect of tetrabromoaluminate ion on the ortho/para ratio the noninvolvement of the proton as a cocatalyst. J. Chem. Soc., Perkin Trans. 2 1989, 2133-2139. 

Ramamurthy and coworkers studied the photo-Fries rearrangement of phenyl acetate and phenyl benzoate and photo-Claisen rearrangement of allyl phenyl ether (Fig. 34) included in two types of zeolite (faujasites X and Y and pen-tasils ZSM-5 andZSM-11) [192], The photolysis was performed with the zeolite slurry in either hexane or iso-octane. One of the most remarkable observations is that the product distribution is altered within zeolites from that in isotropic solvent. Furthermore, while in solution, nearly a 1 1 mixture of ortho and para isomers 40 and 41 (Fig. 34) was obtained, within zeolites one is able to direct the photoreaction selectively toward either the ortho or the para products by conducting the reaction either within faujasites or pentasils, respectively (Fig. 34). 

Figure 34 Photo-Fries rearrangement of phenyl acetate and phenyl benzoate, and photo-Claisen reaction of allyl phenyl ether in solution and within zeolites.

Zeolites H-BEA and H-Y were found to be the most active catalysts, however all catalysts readily form the phenyl benzoate (Table 4.1). In the conditions of the reaction, the formation of phenyl benzoate (PB) occurs rapidly via O-acylation of phenol. Direct C-alkylation of phenol with benzoic anhydride (B) and Fries rearrangement of phenyl benzoate results in the formation of 2- and 4-hydroxy-benzophenones (2-HPB and 4-HPB) (Scheme 4.3). 

The photolysis of phenyl benzoate 8.88 is an example of the photo-Fries rearrangement, in which the acyl radical is created close to a phenoxy radical 8.89. The C—O bond is weakened by the presence of an electron in the n orbital of the ester conjugated system. The radical coupling then shows the usual selectivity for C—C bond formation, with the para selectivity in line with the coefficients of the SOMO of the phenoxy radical (see page 291). 

Heating a phenol ester in the presence of Nafion-H gave good yields of the hydroxy phenyl ketone.This Fries rearrangement gave a mixture of the ortho and para hydroxy compounds in a 1 2-2.5 ratio (Eqn. 22.19). A study of the rearrangement of phenyl benzoate over a number of solid acid catalysts indicated that Nafion-H was more effective than montmorilIonite or amorphous aluminum silicate for this reaction. " ... 

Dewar, M. J. S., Hart, L. S. Aromatic rearrangements in the benzene series. I. Fries rearrangement of phenyl benzoate the benzoylation of phenol. Tetrahedron 1970, 26, 973-1000. 

The photoreactivity of phenyl benzoates in which the para positions of both rings are substituted has been examined in liquid crystalline media and compared with the results obtained in isotropic solution.The photoreactivity of phenyl esters of cyclohexane carboxylic acids in which the para position of the phenyl ring and the 4-position of the cyclohexane ring are substituted were also studied under the same conditions.The products were not identified but were assumed to arise from photo-Fries rearrangement based upon the development of absorption in the ultra-violet spectrum assignable to ortho-hydroxyphenyl ketones. The relative quantum yields of the rearrangements were correlated with the viscosity and order of the liquid crystalline phase. 

Phenyl benzoate (PB) was chosen as a model for the double Fries rearrangement of diphenyl benzoate into diphenol para monomers (Eq. 4) [4] and its transformation over several solid catalysts was investigated [4,8]. 

Table 5.9 Fries rearrangement of phenyl benzoates in the presence of [mim]+Al2Cl7 at 120°C for 2 h...

The Fries rearrangement of phenol esters can lead to the attachment of the carbonyl group to either the o- or the p-position with respect to the phenol. Geneste and co-workers (Chiche et al., 1986 Brunei et al., 1989) have found that rearrangement of phenyl benzoate is best catalyzed by the acidic zeolite HY (Si/Al ratio 15 1), giving a conversion of 38% with an ojp ratio of 15 1 (not possible by conventional AICI3 catalysis). 

Alternatively, the Fries rearrangement has also been observed in ionic melts [79] when phenyl benzoates are shown to rearrange using l-butyl-3-methylimidazolium chloroaluminate ([BMlmi+AljClj) as both a solvent and Lewis acid catalyst. Good yields and high selectivity are the features observed in this unconventional but interesting aprotic solvent the rate of consumption of phenyl benzoate obeys first-order kinetics [79]. 

Also obtained by photo-Fries rearrangement of phenyl benzoate,... 

Also obtained (by-product) by Fries rearrangement of phenyl o-benzoyloxy-benzoate with aluminium chloride at 180° for 3 h (26%) [155]. 

Also obtained by Fries rearrangement of phenyl m-methoxy-benzoate (phenyl m-anisate) with aluminium chloride at 120° or 160° for 2 h [340],... 

Preparation by Fries rearrangement of 2,4-difluoro- — / — / phenyl benzoate with aluminium chloride at 150-180°... 

Preparation by Fries rearrangement of 3-chloro-phenyl benzoate without solvent,... 

Preparation by Fries rearrangement of o-chloro-phenyl benzoate with aluminium chloride without solvent for 2 h at 152-155° (88%) [506] or at 160° [490,491]. 

Also obtained (by-product) by diazotization of 2-amino-5-nitrobenzophenone (4%). The 2-nitrofluorenone was the major compound obtained (75%) [539]. Also obtained (poor yield) by Fries rearrangement of p-nih Ophenyl benzoate with aluminium chloride in nitrobenzene at 170° for 1 h (4%) [540]. Preparation from 2-nitrothioxanthen-9-one 10,10-dioxide (SM) by a three-step synthesis SM by refluxing in a solution of 2% sodium hydroxide in dioxane/ water mixture (65 35) for 2 h, gave the 2-(2-hydroxy-5-nitrobenzoyl)phenyl-sulfmic acid (89%). The former by reaction with mercuric chloride in refluxing aqueous acetic acid for 4 h led to the 2-chloromercuri-2 -hydroxy-5 -nitro-benzophenone (82%). Removal of the chloromercury group was achieved with concentrated hydrochloric acid in refluxing ethanol for 2 h (84%) [62]. 

Obtained (poor yield) by Fries rearrangement of m-nitro-phenyl benzoate with titaninm tetrachloride in benzene or in nitromethane at 40° for 25 h (3%) [36]. 

Also obtained by photo-Fries rearrangement of p-isopropyl-phenyl benzoate in pentane, with or without silica gel (32-35%) [64]. 

Obtained (poor yields) by photo-Fries rearrangement of two substituted phenyl esters in C(CH3)3 benzene [154],M-tert-butyl-2-chlorophenyl benzoate (7%) ... 

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