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Synthesis 1997; 1997(10): 1115-1127
DOI: 10.1055/s-1997-1333
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Zirconium Alkoxide Catalyzed Oxidation of Phenols, Alcohols, and Amines

Karsten Krohn*
  • *Universität-Gesamthochschule Paderborn, Fachbereich 13, Chemie und Chemietechnik, Fachgebiet Organische Chemie, Warburger Str. 100, D-33098 Paderborn, Germany, Fax +49(5251)603245; E-mail: kk@chemie.uni-paderborn.de
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Publication Date:
31 December 2000 (online)

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The development of the zirconium alkoxide catalyzed oxygenation and dehydrogenation is described. Mono-, di- and tri-nuclear phenols are selectively oxidized to the corresponding ortho-quinones. Oxygenation also takes place with 2-alkylated phenols yielding highly functionalized α-hydroxy ketones. A very fast dehydrogenation of benzylic alcohols to the corresponding aldehydes and ketones occurs with the system Zr(O-n-Pr)4/hydroperoxide. Non-activated alcohols are also readily oxidized using the more active Zr(O-t-Bu)4/hydroperoxide or Zr(O-t-Bu)4/chloral system, higher reaction temperatures, and rigorous trapping of water with powdered molecular sieves. Silyl enol ethers are converted to the α-chloro ketones with the system ClTi(O-i-Pr)3/hydroperoxide and phenols are selectively halogenated in the para-position by the same system. Electron-donor as well as electron-acceptor substituted anilines are oxidized in good yields to the corresponding nitro compounds with the Zr(O-t-Bu)4/hydroperoxide system.

ortho-quinones - zirconium catalysis - tert-butyl hydroperoxide oxygenation - alcohols - aldehydes - ketones - anilines - nitro compounds