Lewis Base Catalyzed [4+2] Annulation of Electron‐Deficient Chromone‐Derived Heterodienes and Acetylenes

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.