Organic redox cascade cyclization of 2-alkynylquinones by ascorbic acid in combination with a copper catalyst and its application to formal synthesis of liphagal

Abstract

A stoichiometric amount of ascorbic acid in combination with CuCl₂·2H₂O catalyst was found to promote the organic redox cascade transformation of alkynylquinones, successfully furnishing hydroxybenzofuran derivatives. By applying the present organic redox-driven copper-catalyzed cyclization protocol, a formal synthetic route to liphagal has been developed.