- Electroorganic reactions. Part 56: Anodic oxidation of 2-methyl- and 2-benzylnaphthalenes: Factors influencing competing pathways
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A systematic investigation of the anodic oxidation in nucleophilic media of 2-methyl and 2-benzylnaphthalenes, substituted at the 6-position in the naphthalene nucleus and at the 4-phenyl position of the benzylic side chain, has been carried out to identify factors favouring side-chain substitution. Cyclic voltammetry confirms that 6-substitution has a profound effect on the oxidation potentials of the naphthalene nucleus and 13C chemical shifts indicate polar effects at the benzylic carbon. However, little side-chain anodic oxidation is observed under any conditions tried; the radical-cations of electron-rich substrates preferentially dimerise and a strongly electron-withdrawing substituent at the 6-position (EtOSO2) promotes nuclear substitution. In contrast, oxidation with DDQ in aqueous acetic acid gives efficient side-chain oxidation for electron rich substrates, consistent with hydride transfer, possibly intramolecularly via a charge transfer complex.
- Utley, James H.P,Rozenberg, Gregor G
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p. 5251 - 5265
(2007/10/03)
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- Anodic Oxidation of Xylenes. Electrochemical Obtention of Cyclohexa-1,4-diene Derivatives
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cis- and trans-3,6-dimethoxy-3,6-dimethylcyclohexa-1,4-dienes obtained by methoxylation of p-xylene were completely separated.The unequivocal structure of the trans isomer was assigned by X-ray diffraction, and the cis:trans ratio is satisfactorily explained by an EECrCp mechanism.When the substrates were p- and o-xylene, the nuclear-addition products were obtained in a two-electron process, but when the substrate was m-xylene, the major muclear-addition product was obtained in a four-electron process.
- Barba, Isidoro,Alonso, Francisco,Florencio, Feliciana
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p. 4365 - 4367
(2007/10/02)
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