Regioselective Synthesis of Prenylisoflavones. Syntheses of Lupiwighteone, Lupiwighteone Hydrate and Related Compounds

Abstract

Catalytic hydrogenation and the subsequent dehydration of 8-(3-hydroxy-3-methylbutynyl)isoflavone 12, which was synthesized by the palladium-catalyzed coupling reaction of 4′,5,7-tris(benzyloxy)-8-iodoisoflavone 11 with 2-methyl-3-butyn-2-ol, gave a mixture of 8-prenylisoflavone 16 and the isomer [5-acetoxy-8-(3-methyl-3-butenyl)isoflavone] 17, and after the separation of 16 was accomplished by treatment of the mixture with Hg(NO₃)₂, hydrolysis of 16 afforded 4′,5,7-trihydroxy-8-prenylisoflavone (lupiwighteone) 1.