Synthesis of Isoflavones by Tandem Demethylation and Ring-Opening/Cyclization of Methoxybenzoylbenzofurans

The unexpected conversion of benzoylbenzofurans into isoflavones through an intramolecular cascade that involves deprotection and ring-opening/cyclization is described. This was discovered in an investigation of the possible transformation of benzoylbenzofurans into coumaronochromones. This route affords isoflavones in two major steps from acetophenones and benzoquinones. The transformation was validated by synthesizing differently substituted isoflavone derivatives and further applied to a concise synthesis of a potential anticancer lead compound, glaziovianin A (1).