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Volumn 69, Issue 10, 2004, Pages 3465-3473

Aryl Cations from Aromatic Halides. Photogeneration and Reactivity of 4-Hydroxy(methoxy)phenyl Cation

Author keywords

[No Author keywords available]

Indexed keywords

BENZENE; COMPLEXATION; DEHALOGENATION; OLEFINS; PHENOLS; SOLVENTS;

EID: 2442557088     PISSN: 00223263     EISSN: None     Source Type: Journal    
DOI: 10.1021/jo049770+     Document Type: Article
Times cited : (67)

References (51)
  • 8
    • 2442546317 scopus 로고    scopus 로고
    • note
    • Differently from the triplet, singlet aryl cations behave as unselective electrophiles and reaction with the solvent is usually observed also in the presence of π nucleophiles. See ref 4
  • 22
    • 2442574678 scopus 로고    scopus 로고
    • note
    • The salt is completely soluble in MeOH or TFE but slightly soluble in the other solvents.
  • 23
    • 2442631263 scopus 로고    scopus 로고
    • note
    • (a) Laser flash photolysis experiments on 4-chlorophenol in acetonitrile did not reveal any triplet signal. See ref 8a.
  • 24
    • 2442571808 scopus 로고    scopus 로고
    • note
    • (b) Evidence for a similar mechanism in the reduction of the analoguous 4-aminophenyl cation has been presented; see ref 2b. A study on the mechanism of the photoreaction of 1 in alcoholic solvents is underway.
  • 25
    • 2442504496 scopus 로고    scopus 로고
    • note
    • We have no positive evidence for the phenonium structure of the adduct cation, but this is calculated to be the lowest-lying adduct with an alkene; see ref 2a.
  • 27
    • 2442418717 scopus 로고    scopus 로고
    • note
    • For example, the quantum yield of photodegradation in MeOH is reported to be φ = 0.1, whereas in cyclohexane it is somewhat higher at φ = 0.35. See ref 11.
  • 28
    • 0001010887 scopus 로고
    • and ref 4
    • Singlet aryl cation are to our knowledge obtained only from the photolysis of diazonium salt (see Gasper, S.; Devadoss, C.; Schuster, G. B. J. Am. Chem. Soc. 1995, 117, 5206-5211 and ref 4)
    • (1995) J. Am. Chem. Soc. , vol.117 , pp. 5206-5211
    • Gasper, S.1    Devadoss, C.2    Schuster, G.B.3
  • 30
    • 0003940950 scopus 로고
    • Elsevier: Amsterdam
    • At any rate, the carbene would be expected to give isolable spirocyclopropyleyclohexadienones rather than alkylated phenols; see: Ershov, V. V.; Nikiforov, G. A.; de Jonge, C. R. Quinone Diazides; Elsevier: Amsterdam, 1981.
    • (1981) Quinone Diazides
    • Ershov, V.V.1    Nikiforov, G.A.2    De Jonge, C.R.3
  • 35
    • 0142182797 scopus 로고    scopus 로고
    • The role of the formation of the hydrogen-halide bond in facilitating the heterolysis of the triplet has been demonstrated for 4-fluoroanilines. See: Freccero, M.; Fagnoni, M.; Albini, A. J. Am. Chem. Soc. 2003, 125, 13182-13190.
    • (2003) J. Am. Chem. Soc. , vol.125 , pp. 13182-13190
    • Freccero, M.1    Fagnoni, M.2    Albini, A.3
  • 36
    • 0346970844 scopus 로고    scopus 로고
    • The growing interest in the use of fluorinated alcohols in organic synthesis, as a result of the clean and selective reactions obtained, is apparent in a recent review: Bégué, J.-P.; Bonnet-Delpon, D.; Crousse, B. Synlett 2004, 18-29.
    • (2004) Synlett , pp. 18-29
    • Bégué, J.-P.1    Bonnet-Delpon, D.2    Crousse, B.3
  • 37
    • 2442624337 scopus 로고    scopus 로고
    • note
    • The effect of addition of cesium carbonate is complex. It somewhat enhances the conversion of chlorophenol 1, reasonably because some phenolate anion is then present, which absorbs a large proportion of the light used for irradiation (lamps centered at 310 nm) since its absorption is red-shifted by ca. 10 nm. This effect seems more important for 1 in polar nonprotic solvents despite the slight solubiblity of the base in this medium. In particular, in ethyl acetate the addition of cesium carbonate increased the conversion of 1 from 11% to 50%, with a concomitant increase of the photoreduction yield. Even if the phenolate absorbs part of the light, the photoproducts distribution did not change, in accord with previous reports.8a,25 In accord with this rationalization, the reactivity of a nonacidic compound such as anisole 2 was affected to a much lower degree.
  • 39
    • 2442615828 scopus 로고    scopus 로고
    • note
    • 28 applies to electrophilic but not nucleophilic alkenes.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.