Construction of the Tetracyclic Core Structure of Dysiherbols A-C.

A synthetic study on the construction of the tetracyclic core structure of dysiherbols A-C is presented herein. In this synthesis, intramolecular [2 + 2] cycloaddition introduces a fused 6/4 ring system, followed by a Pd-catalyzed semipinacol rearrangement/C sp2 -H arylation cascade to construct the ring C, and visible-light-mediated ring-opening of cyclopropyl silyl ether installs the tetracyclic core of dysiherbols.