title: Possible intermediates of Cu(phen)-catalyzed C-O cross-coupling of phenol with an aryl bromide by in situ ESI-MS and EPR studies.
abstract: The C-O coupling reaction between 2,4-dimethylphenol and 4-bromotoluene catalyzed by the CuI/K2CO3/phen system can be inhibited by the radical scavenger cumene. Complexes [Cu(i)(phen)(1-(2,4-dimethylphenoxy)-4-methylbenzene)](+) (denoted as A), {H[Cu(i)(phen)(2,4-dimethylphenoxy)]}(+) and [Cu(i)(2,4-dimethylphenoxy)2](-) (denoted as B) were observed by in situ electrospray ionization mass spectrometry (ESI-MS) analysis of the copper(i)-catalyzed C-O coupling reaction under the catalytic reaction conditions indicating that they could be intermediates in the reaction. The in situ EPR study of the reaction solution detected the Cu(ii) species with a fitted g value of 2.188. A catalytic cycle with a single electron transfer (SET) step was proposed based on these observations.
authors.affiliation: Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan, Republic of China. sgshyu@chem.sinica.edu.tw.
authors.forename: Hong-Jie
authors.initials: HJ
authors.lastname: Chen
authors.forename: I-Jui
authors.initials: IJ
authors.lastname: Hsu
authors.forename: Mei-Chun
authors.initials: MC
authors.lastname: Tseng
authors.forename: Shin-Guang
authors.initials: SG
authors.lastname: Shyu
mesh_terms: D001555:Benzene Derivatives / Q000494:pharmacology; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D016166:Free Radical Scavengers / Q000494:pharmacology; D015394:Molecular Structure; D010100:Oxygen / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D014050:Toluene / Q000031:analogs & derivatives* / Q000737:chemistry; D014992:Xylenes / Q000737:chemistry*
chemical_list: D001555:Benzene Derivatives; D016166:Free Radical Scavengers; D014992:Xylenes; D014050:Toluene; C027804:2,4-dimethylphenol; D003300:Copper; C015763:cumene; C491446:4-bromotoluene; D010100:Oxygen