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Keywords:

  • Science & Technology
  • Multidisciplinary Sciences
  • Science & Technology - Other Topics
  • FUNCTIONALIZATION
  • SELECTIVITY
  • ACTIVATION
  • REAGENTS
  • DIOXYGEN
  • INDOLES
  • BONDS

Tailored quinones support high-turnover Pd catalysts for oxidative C-H arylation with O-2

Tools:

Journal Title:

SCIENCE

Volume:

Volume 370, Number 6523

Publisher:

, Pages 1454-1460

Type of Work:

Article

Abstract:

Palladium(II)-catalyzed carbon-hydrogen (C-H) oxidation reactions could streamline the synthesis of pharmaceuticals, agrochemicals, and other complex organic molecules. Existing methods, however, commonly exhibit poor catalyst performance with high palladium (Pd) loading (e.g., 10 mole %) and a need for (super)stoichiometric quantities of undesirable oxidants, such as benzoquinone and silver(I) salts. The present study probes the mechanism of a representative Pd-catalyzed oxidative C-H arylation reaction and elucidates mechanistic features that undermine catalyst performance, including substrate-consuming side reactions and sequestration of the catalyst as an inactive species. Systematic tuning of the quinone cocatalyst overcomes these deleterious features. Use of 2,5-di-tert-butyl-p-benzoquinone enables efficient use of molecular oxygen as the oxidant, high reaction yields, and >1900 turnovers by the Pd catalyst.
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