Photo‐Fries Rearrangement and Related Photochemical [1,j] ‐Shifts (j = 3, 5, 7) of Carbonyl and Sulfonyl Groups

Belluš, D.

doi:10.1002/9780470133385.ch3

Cited by 181 publications

(17 citation statements)

References 86 publications

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“…These estrone derivatives 1 – 4 bearing a sulfonic ester group on the phenyl ring of the steroids became interesting substrates to study the possible photo‐Fries rearrangement under direct irradiation ( λ exc = 254 nm). Anderson and Reese (27) have discovered the photo‐Fries rearrangement reaction in 1960 and later it was demonstrated that the photoreaction involves the homolytic fragmentation of the carbon–heteroatom bond, that is, C‐O, C‐S and C‐N, characteristic bonds present in esters, thioesters and amides, respectively (28). Usually, the photoreaction provided the ortho‐ and para‐ regioisomers along with the corresponding phenols, thiophenols or amines, depending on the nature of the carbon–heteroatom bond cleaved (29).…”

Section: Introductionmentioning

confidence: 99%

Photochemical Behavior of Some Estrone Aryl and Methyl Sulfonates in Solution: Preparative and Mechanistic Studies

Quindt

Gola

Ramírez

et al. 2020

Photochem & Photobiology

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Direct irradiation of estrone aryl and methyl sulfonates in different organic solvents under nitrogen atmosphere was investigated under steady‐state conditions. The estrone derivatives reacted efficiently through the photo‐Fries rearrangement reaction involving [1;3]‐sulfonyl migration providing the ortho‐sulfonyl estrone derivatives and estrone as the photoproducts. In addition, estrone and 2‐arylsulfonyl estrone derivatives were epimerized involving a Norrish Type‐I reaction. Chemical quenching and photosensitization experiments on the photoreaction have been also carried out to establish the photoreactive excited state. Likewise, the solvent effect and the nature of the sulfonyl group on the photoreactions have been also studied.

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Section: Introductionmentioning

confidence: 99%

Photochemical Behavior of Some Estrone Aryl and Methyl Sulfonates in Solution: Preparative and Mechanistic Studies

Quindt

Gola

Ramírez

et al. 2020

Photochem & Photobiology

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“…The first reaction investigated was the photo‐Fries rearrangement of naphthyl esters 1 and 6 . The choice of naphthyl system is based on the following factors: (a) Photochemical behavior of these esters has been extensively studied in isotropic solvents (28, 29). (b) Attempts have been made to achieve selectivity in various media with varied success (30–33).…”

Section: Resultsmentioning

confidence: 99%

Alkali Ion Exchanged Nafion as a Confining Medium for Photochemical Reactions†

Arumugam

Kaanumalle

Ramamurthy

2006

Photochem Photobiol

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Methanol-swollen Nafion beads were used as microreactors to control the photochemical reaction pathways. Product selectivity in three unimolecular reactions, namely, the photo-Fries rearrangement of naphthyl esters, Norrish Type I reaction of 1-phenyl-3-p-tolyl-propan-2-one and Norrish Type I and Type II reactions of benzoin alkyl ethers were examined. The influence of cations over the photodimerization of acenaphthylene and cross-photodimerization between acenaphthylene and N-benzyl maleimide included within Nafion were also examined. The photochemical behaviors of the above substrates were significantly altered within Nafion compared with their solution photochemistry. Of particular interest, the product distributions were found to depend on the counter cations of Nafion.

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“…After photo-induced lysis of (R)-1, in-cage combination of radical pair A can reform the starting ester or form the keto intermediates of the eventually isolated photo-Fries rearrangement products, (Bellus 1971, Martin 1992, Miranda 1995, Miranda and Galindo 2003a; tautomerization of the keto intermediates (Mori et al 2004b) occurs rapidly on the time scale of our laboratory manipulations, even in saturated paraffins. The apparent and actual 1,3-and 1,5-sigmatropic H-shifts occur in the range of microsecond to seconds, depending strongly on the nature of the solvent, and many are intermolecular (Chiang et al 1984a, b, Arai et al 1994.…”

Section: Combinations Of Radical Pairs a And B From (R)-1 General Comentioning

confidence: 92%

“…In part because the viscosities of n-hexane (0.3036 cP) and ethyl acetate (0.426 cP) (Timermans 1965) are similar at 23 • C, the regioselectivities of the radical pair combinations in the two solvents are somewhat similar: 2AN/4AN >> 1 and 2BN/4BN << 1 and the 2AN/4AN ratios suggest that radical pair A combines predominantly in-cage in both solvents (Bellus 1971, Martin 1992, Miranda 1995, Miranda and Galindo 2003a. The initial orientation of radical pair A places the radical center of 2-phenylpropanoyl closer to C(2) than to C(4) of its 1-naphthoxy radical partner (Figure 1) (Xu and Weiss 2005a).…”

Section: Radical Pair Combinations In Ethyl Acetate; Comparisons Withmentioning

confidence: 99%

Photo-Fries rearrangements of 1-naphthyl (R)-2-phenylpropanoate in poly(vinyl acetate) and ethyl acetate: influence of medium polarity and polymer relaxation on motions of singlet radical pairs

George

Weiss

2006

An. Acad. Bras. Ciênc.

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Both the regio-and stereo-chemistries of the photoreactions of 1-naphthyl (R)-2-phenylpropanoate have been investigated in poly(vinyl acetate) films in their glassy (at 5 • C) and melted (at 50 • C) states and in ethyl acetate. These results are compared with those from irradiations in polyethylene films and in n-hexane. The regioselectivity of the intermediate 1-naphthoxy/(R)-2-phenylpropanoyl radical pair combinations is much higher in both the melt and glassy states of poly(vinyl acetate) films than that in the melt state of completely amorphous polyethylene films, but the stereoselectivity of intermediate prochiral 1-naphthoxy/1-phenylethyl radical pair combinations is much lower in poly(vinyl acetate). The results emphasize the need to control the ratio between the rates of radical tumbling and translation, as well as the ratio between the rates of in-cage motions and cage-escape, if high stereo-and regio-selectivities of combination products are to be achieved. A mechanistic picture of how the radicals of the intermediate pairs are affected by and interact with the various media is advanced.

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Photo‐Fries Rearrangement and Related Photochemical [1,j] ‐Shifts (j = 3, 5, 7) of Carbonyl and Sulfonyl Groups

Cited by 181 publications

References 86 publications

Photochemical Behavior of Some Estrone Aryl and Methyl Sulfonates in Solution: Preparative and Mechanistic Studies

Photochemical Behavior of Some Estrone Aryl and Methyl Sulfonates in Solution: Preparative and Mechanistic Studies

Alkali Ion Exchanged Nafion as a Confining Medium for Photochemical Reactions†

Photo-Fries rearrangements of 1-naphthyl (R)-2-phenylpropanoate in poly(vinyl acetate) and ethyl acetate: influence of medium polarity and polymer relaxation on motions of singlet radical pairs

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