Laccase-catalyzed domino reactions between hydroquinones and cyclic 1,3-dicarbonyls for the regioselective synthesis of substituted p-benzoquinones

J Org Chem. 2012 Jan 6;77(1):445-59. doi: 10.1021/jo202082v. Epub 2011 Dec 12.

Abstract

Highly substituted p-benzoquinones were obtained in yields ranging from 39% to 98% by laccase-catalyzed domino reactions between hydroquinones and cyclic 1,3-dicarbonyls using aerial oxygen as the oxidant. In almost all reactions bis-adducts with two adjacent 1,3-dicarbonyl substituents on the quinone moiety were formed selectively. The transformations can be regarded as domino oxidation/1,4-addition/oxidation/1,4-addition/oxidation processes. With unsubstituted hydroquinone as the substrate 2,3-disubstituted p-benzoquinones were isolated. Bis-adducts were also formed exclusively upon reaction with monosubstituted hydroquinones. In almost all cases the 2,3,5-trisubstituted p-benzoquinones were obtained. When 2,3-disubstituted hydroquinones were employed as starting materials the 2,3,5,6-tetrasubstituted p-benzoquinones were isolated. The unambiguous structure elucidation of all products has been achieved by NMR spectroscopic methods including spin pattern analysis of the long-range coupled C═O carbons and (13)C satellites analysis in (1)H NMR spectra.

MeSH terms

  • Benzoquinones / chemical synthesis*
  • Benzoquinones / chemistry*
  • Catalysis
  • Hydroquinones / chemistry*
  • Laccase / chemistry*
  • Magnetic Resonance Spectroscopy
  • Molecular Structure
  • Oxidation-Reduction

Substances

  • Benzoquinones
  • Hydroquinones
  • Laccase