SEARCH

SEARCH BY CITATION

Keywords:

  • annulation;
  • benzopyrones;
  • Lewis bases;
  • natural products;
  • organocatalysis

Abstract

Lewis base catalyzed [4+2] annulation reactions between electron-deficient chromone oxa- and azadienes and acetylene carboxylates provide tricyclic benzopyrones inspired by natural products. An asymmetric synthesis of the tricyclic benzopyrones was developed by using modified cinchona alkaloids as enantiodifferentiating Lewis base catalysts.