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

4 ' ,5,7-Trihydroxy- or 8-alkyl-4 ' .5,7-trihvclroxycoumaronochromones 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. (C) 2001 Elsevier Science Ltd. All rights reserved.