Asymmetric Synthesis of Cycloartobiloxanthone

Herein, we report the first asymmetric synthesis of cycloartobiloxanthone, a polycyclic dihydroxanthone natural product. Our convergent synthesis employs a rhodium-catalyzed C-H insertion reaction to construct the key fused tricyclic core with high enantioselectivity. Two fragments were joined together by a displacement reaction and a Friedel-Crafts acylation to generate the dihydroxanthone core. This synthesis offers a promising foundation for accessing structurally related dihydroxanthone natural products and analogues for structure-activity relationship studies.