Regioselective Synthesis of 6-Alkyl- and 6-Prenylpolyhydroxyisoflavones and 6-Alkylcoumaronochromone Derivatives

Abstract

The palladium-catalyzed coupling reaction of 6-iodoisoflavone, prepared from 3′-iodoacetophenone derivative, with 2-methyl-3-butyn-2-ol gave 6-alkynylisoflavone derivative, which was hydrogenated to give 6-alkylhydroxyisoflavone (luteone hydrate) (2). Dehydration of 2 gave 2′,4′,5,7-tetrahydroxy-6-prenylisoflavone (luteone) (1). Wighteone hydrate (3) was also synthesized from 6-iodotris(benzyloxy)isoflavone in a similar manner. 6-Alkyl-4′5,7-trihydroxy-coumaronochromone (4) was synthesized by oxidative cyclization of 2 with o-chloranil.