Total Synthesis of Cavicularin and Riccardin C: Addressing the Synthesis of an Arene That Adopts a Boat Configuration

摘要

From a structural perspective cavicularin (1), from the liverwort Cavicularia densa,[1] is one of the most unusual natural products to have been isolated in the last decade. It comprises a macrocyclic core that contains dibenzyl and dihydrophenanthrene units conjoined by a biaryl bond and an ether linkage. This core imparts such strain on the system that one of the arenes, ring A, adopts a boatlike configuration and is twisted out of the plane by some 15° in the solid state. Herein, we describe the first total synthesis of cavicularin (1), in which a radical-induced transannular ring contraction features as a key step (Scheme 1).