Total synthesis and assignment of the absolute stereochemistry of xanthoangelol J: development of a highly efficient method for Claisen–Schmidt condensation

The first total synthesis of cancer chemopreventive terpenyl hydroxychalcone xanthoangelol J isolated from Angelica keiskei was accomplished with asymmetric epoxidation, aromatic C-alkylation and Claisen–Schmidt condensation via enol mode as key steps. The crucial Claisen–Schmidt condensation has been accomplished by a novel green method using KHSO4–SiO2 as a recyclable catalyst under microwave activation. The absolute configuration of the molecule was also determined.