Dehydrogenation of ketones by pincer-ligated iridium: Formation and reactivity of novel enone complexes

Xiawei Zhang, David Y. Wang, Thomas J. Emge, Alan S. Goldman

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25 Citations (Scopus)

Abstract

The transfer dehydrogenation of several ketones by (PCP)IrH2 (PCP = κ3-C6H3-2,6-(CH2P tBu2)2) (1) has been observed. Catalytic turnover was inhibited in most cases by the formation of stable metallacycles or the O-H oxidative addition of phenolic products. Catalytic transfer dehydrogenation of 3,3-dimethylcyclohexanone was achieved, giving the corresponding α,β-enone. The transfer dehydrogenation reaction of cycloheptanone with 1 was found to generate a surprisingly stable PCP-iridium troponyl hydride (9), which is stabilized by conjugation and possibly represents an unusual bicyclo[5.2.0]troponyliridium metalloaromatic structure. Complex 9 was found to catalyze the dimerization of tropone to give a fused tricyclic dihydrodicycloheptafuranol. A mechanism for this reaction is proposed wherein the coordinated troponyl group nucleophilically attacks a free tropone molecule.

Original languageEnglish
Pages (from-to)253-259
Number of pages7
JournalInorganica Chimica Acta
Volume369
Issue number1
DOIs
Publication statusPublished - Apr 15 2011

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Keywords

  • Organometallic homogeneous catalysis
  • PCP pincer-ligated iridium complexes
  • Transfer dehydrogenation of ketones
  • Tropone dimerization
  • X-ray crystal structures

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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