A concise synthesis of licochalcone E and its regio-isomer, licochalcone F.

Licochalone E is one of the retrochalcones isolated from Glycyrrhiza inflata which shows potent cytotoxicty against human tumor cell lines. Biological studies suggested that topoisomerase I inhibition correlates with cytotoxic properties. Other research revealed that licochalcone E modulats the nuclear factor (NF)-kB and Bcl-2 families to induce endothelial cell apoptosis. Since licochalcone E has been isolated recently, synthetic information on this compound has not been reported yet. Therefore we report the concise synthesis of licochalcone E and its regio-isomer, tentatively called licochalcone F, by employing Claisen rearrangement for key intermediate synthesis.