Efficient and selective aerobic oxidation of alcohols into aldehydes and ketones using ruthenium/TEMPO as the catalytic system

J Am Chem Soc. 2001 Jul 18;123(28):6826-33. doi: 10.1021/ja0103804.

Abstract

The combination of RuCl2(PPh3)3 and TEMPO affords an efficient catalytic system for the aerobic oxidation of a variety of primary and secondary alcohols, giving the corresponding aldehydes and ketones, in >99% selectivity in all cases. The Ru/TEMPO system displayed a preference for primary vs secondary alcohols. Results from Hammett correlation studies (rho = -0.58) and the primary kinetic isotope effect (kH/kD = 5.1) for the catalytic aerobic benzyl alcohol oxidations are inconsistent with either an oxoruthenium (O=Ru) or an oxoammonium based mechanism. We postulate a hydridometal mechanism, involving a "RuH2(PPh3)3" species as the active catalyst. TEMPO acts as a hydrogen transfer mediator and is either regenerated by oxygen, under catalytic aerobic conditions, or converted to TEMPH under stoichiometric anaerobic conditions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aerobiosis
  • Alcohols / chemistry
  • Alcohols / metabolism*
  • Aldehydes / chemistry
  • Aldehydes / metabolism*
  • Catalysis
  • Cyclic N-Oxides / chemistry
  • Cyclic N-Oxides / metabolism*
  • Ketones / chemistry
  • Ketones / metabolism*
  • Oxidation-Reduction
  • Ruthenium / chemistry
  • Ruthenium / metabolism*
  • Spin Labels

Substances

  • Alcohols
  • Aldehydes
  • Cyclic N-Oxides
  • Ketones
  • Spin Labels
  • Ruthenium
  • TEMPO