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.