Environmentally Benign Synthesis of Isoflavone Derivatives Using Polymer-Supported Hypervalent Iodine(III) Reagent

Abstract

Isoflavones are synthesized in one-pot manner by action of a hypervalent iodine (III) reagent, ⌊hydroxy(tosyloxy)iodo⌋benzene (HTIB, Koser's reagent) on 2'-benzoyloxychalcones in MeOH. A combined usage of iodobenzene diacetate (IBD)—p-toluenesulfonic acid (TsOH) is also effective for the same purpose. As an extension of those monomeric reagents, polymer-supported IBD (PSIBD, poly ⌊4-(diacetoxy)iodo⌋styrene) with TsOH works also well with merit of easy separation of isoflavones from the reaction mixture, no liberation of PhI, and reuse of the reagent.