Total Synthesis of Riccardin C and (±)-Cavicularin via Pd-Catalyzed Ar-Ar Corss Couplings.
K. Harada, K. Makino, N. Shima, H. Okuyama, T. Esumi, M. Kubo, H. Hioki, Y. Asakawa, Y. Fukuyama.
Riccardin C, a specific LXR α agonist, is a representative macrocyclic bisbibenzyl-type natural product. As part of our synthetic studies on macrocyclic bisbibenzyls, the synthesis of riccardin C and its analog cavicularin was examined. The total synthesis of riccardin C was accomplished via a Pd-catalyzed intramolecular Suzuki-Miyaura coupling as the key macrocyclization step. This synthetic strategy was also extended in the synthesis of (±)-cavicularin, which was then attained by constructing the dihydrophenanthrene moiety using a Pd-catalyzed Ar-Ar coupling reaction.