A concise synthesis of polyhydroxydihydrochalcones and homoisoflavonoids

A general and single step synthesis of polyhydroxydihydrochalcones from the readily available phenols and dihydrocinnamic acids using BF3-Et2O is described. The method allows the synthesis of a wide range of compounds with multiple phenolic hydroxyls and other substituents. These dihydrochalcones are converted into homoisoflavonoids by DMF/PCl5 and the methodology has been applied to the synthesis of naturally occurring phloretin and 5,7-dihydroxy-3-[(4-hydroxyphenyl)methyl]-4H-chromen-4-one. The antioxidant activity of dihydrochalcones and homoisoflavonoids was determined by superoxide free radical (NBT) and DPPH free radical scavenging methods. Polyhydroxydihydrochalcones 3c, 3f, 3g and homoisoflavonoids 4c, 4f, 4g displayed excellent antioxidant activity. (c) 2005 Elsevier Ltd. All rights reserved.