Benzoyl radicals from (hetero)aromatic aldehydes. Decatungstate photocatalyzed synthesis of substituted aromatic ketones

Org Biomol Chem. 2010 Sep 21;8(18):4158-64. doi: 10.1039/c0ob00066c. Epub 2010 Jul 27.

Abstract

Benzoyl radicals are generated directly from (hetero)aromatic aldehydes upon tetrabutylammonium decatungstate ((n-Bu(4)N)(4)W(10)O(32)), TBADT) photocatalysis under mild conditions. In the presence of alpha,beta-unsaturated esters, ketones and nitriles radical conjugate addition ensues and gives the corresponding beta-functionalized aryl alkyl ketones in moderate to good yields (stereoselectively in the case of 3-methylene-2-norbornanone). Due to the mild reaction conditions the presence of various functional groups on the aromatic ring is tolerated (e.g. methyl, methoxy, chloro). The method can be applied to hetero-aromatic aldehydes whether electron-rich (e.g. thiophene-2-carbaldehyde) or electron-poor (e.g. pyridine-3-carbaldehyde).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aldehydes / chemistry*
  • Catalysis
  • Free Radicals / chemical synthesis
  • Free Radicals / chemistry
  • Ketones / chemical synthesis*
  • Ketones / chemistry*
  • Molecular Structure
  • Nitriles / chemistry
  • Photochemistry
  • Quaternary Ammonium Compounds / chemistry*
  • Tungsten Compounds / chemistry*

Substances

  • Aldehydes
  • Free Radicals
  • Ketones
  • Nitriles
  • Quaternary Ammonium Compounds
  • Tungsten Compounds
  • tetrabutylammonium