Facile synthesis of polyhydroxycoumaronochromones with quinones: synthesis of alkylpolyhydroxy- and alkoxycoumaronochromones from 2′-hydroxyisoflavones

4′,5,7-Trihydroxy- or 8-alkyl-4′,5,7-trihydroxycoumaronochromones were synthesized by oxidative cyclization of the corresponding 2′-hydroxyisoflavones with o-chloranil under mild conditions. By contrast, alkoxycoumaronochromones were synthesized by oxidative cyclization of the corresponding 2′-hydroxyisoflavones with DDQ.