Naphthyl acetate, Fries rearrangement

Naphthyl acetates, Fries rearrangement of 639 Naphthylamines—see also 8-Hydroxy-A, Ai-dimethyl-1-naphthylamine as phenol precursors 401, 402 Naringin, complexes of 365 National Institute of Health (NIH) shift 14 Negative ion chemical ionization (NlCl) mass spectrometry 310, 314-316 Negishi reaction 1406 Nematic liquid crystals 372-375 Neolignans 1278... 

The rearrangement of aryl and naphthyl acetates has been reported to be catalyzed by Bi(0Tf)3xH20 (Scheme 9) [68, 69]. As previously reported, only ortho-Fries products (l-hydroxy-2-acylaromatics) were produced from substrates for which ortho acylation was possible. In the case of 2,6-dimethoxyphenyl acetate, only the 3,5-dimethoxy-2-hydroxy acetophenone was produced, indicating that in this case the mechanism involves an intermolecular acyl-group transfer. As in other reactions, the nature of the true catalyst is still unclear since triflic acid also catalyzes this reaction. 

More recently, Mouhtady et al. demonstrated that Bi(0Tf)3xH20 and other metal triflates interact with methanesulfonic acid (MSA) to form an efficient synergic catalytic system for the Fries rearrangement of naphthyl acetate [70, 71]. 

Andrew, D. Des Islet, B. T. Margaritis, A. Weedon, A. C. Photo-Fries Rearrangement of Naphthyl Acetate in Supercritical Carbon Dioxide Chemical Evidence for Solvent-Solute Clustering. J. Am. Chem. Soc. 1995, 117, 6132-6133. 

Cui and Weiss reported the photo-Fries rearrangements of 2-naphthyl myristate and 2-naphthyl acetate (Fig. 35) in unstretched and stretched low-density polyethylene films [116]. It was argued that the radical pair generated by irradiation is held in a cavity shaped like the starting ester and whose walls relax more slowly than the radicals recombine. The preferred solution product is too different in shape from the starting ester to be formed. 

Figure 35 Photo-Fries rearrangement of 2-naphthyl acetates in solution and within low-density polyethylene films.

Figure 36 Photo-Fries rearrangement of 1-naphthyl acetates within Y-zeolite and low-density polyethylene films.

The photochemical Fries rearrangement for 2-naphthyl acetate has been studied in poly(methyl methacrylate) . Products were produced which acted as quenchers and prevented further product formation. 

Bismuth(III) triflate tetrahydrate can be utilized as a more commercially available catalyst for the Fries rearrangement of PAs to 2-hydrox-yaryl ketones. In the reaction with 1-naphthyl acetate, bismuth triflate (10% mol) gives the best yield in 2-acetyl-l-naphthol, the amount of... 

Thus, in the case of PA, ortho-HAF is obtained in 75% isolated yield when irradiated in a microwave oven for 3 min, whereas, when the reaction is carried out with the same quantities in an oil-bath at 60°C for 6 h, para-HAF is obtained in 70% isolated yield. Under microwave irradiation, para-migration takes place, whereas, under oil-bath conditions, ortho-migration is observed. Moreover, 1-naphthyl- and 2-naphthyl acetates undergo the Fries rearrangement at the ortho-position in 85% and 90% isolated yields, respectively, when subjected to microwave irradiation in the presence of zinc powder and dimethylformamide for 10 and 8 min. 

Microwave-induced Fries rearrangement can also be efficiently performed by using an aluminum chloride-zinc chloride mixture supported on silica under solventless conditions. The reaction can be applied to different phenyl and naphthyl acetates. ortho-HAP is isolated in 95% yield... 

In order to address this issue, a process which involves a much shorter-lived radical pair needed to be examined. Toward this end, Weedon, et al. examined the photo-Fries rearrangement of naphthyl acetate (Scheme 4.4-6) in SCCO2 at 35 and 46 C [56]. Photolysis of 1 leads to caged pair [2/3] reaction in-cage yields the photo-Fries products, 2- or 4-acetylnaphthol (4 and 5). However, cage escape, followed by hydrogen abstraction (isopropanol was present as a hydrogen atom donor) leads to a-naphthol (6). 

Serum albumins have been employed as hosts for the photo-Fries rearrangement of 4-methoxy-l-naphthyl esters, at site I (acetate) and site II (monoglutarate) of the proteins. A species- and site-dependent quantum yield of product formation is observed the best results are obtained within site I of bovine serum albumin. ... 

D Andrew, BT Des Islet, A Margaritis, AC Weedon. Photo-Fries rearrangement of naphthyl acetate in supercritical carbon dioxide chemical evidence for solvent-solute clustering. J Am Chem Soc 117 6132-6133, 1995. 

Inorganic mesoporous materials such as zeolites have also served as hosts for aromatic esters whose irradiation leads to changes in the selectivity of the photoproducts ortho preference) in comparison with the rearrangement in homogeneous media., - Finally, the photochemical Fries rearrangement of naphthyl acetate has shown the occurrence of solvent-solute clustering in supercritical carbon dioxide. " ... 

Nakagaki, R, Hiramatsu, M., Watanabe, T, Tanimoto, Y., and Nagakura, S., Magnetic isotope and external magnetic field effects upon the photo-Fries rearrangement of 1-naphthyl acetate, /. Phys. Chem., 89, 3222, 1985. 

Gu, W. Q., Bi, S. G., and Weiss, R. G., Photo-Fries rearrangements of 1-naphthyl esters in the glassy and melted states of poly(vinyl acetate). Comparisons with reactions in less polar polymers and low-viscosity solvents, Photochem. PhotobioL Sci., 1, 52, 2002. 

Photodecarboxylation in the presence of photocatalysts such as TiOj has also been studied. For example, the photodegradation of (4-chloro-2-methylphenoxy)acetic acid, a herbicide, in an aqueous solution of TiOj involves elimination of carbon dioxide from the initially formed radical species on the catalyst surface. The templating of carboxyHc acids with polyethylene films has been found to enhance the photodecarboxylation at the expense of the photo-Fries rearrangement in simple aryl esters such as phenyl and 1-naphthyl esters." ... 

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