An efficient synthesis of the phytoestrogen 8-prenylnaringenin from isoxanthohumol with magnesium iodide etherate

Xanthohumol was isolated from supercritical carbon dioxide–spent hop and transformed into isoxanthohumol. The demethylation of isoxanthohumol with the best yield 93% occurred when MgI2 etherate in anhydrous THF was applied. Salts such as MgBr2, MgCl2, CaI2, Mg(OAc)2, Mg(OMe)2 were also investigated. A convenient method for the xanthohumol isolation from supercritical carbon dioxide–spent hop is also described.