Synthesis of the DFGH ring system of type B physalins: highly oxygenated, cage-shaped molecules.

Let the dominos fall: Synthesis of the complex DFGH ring system of the title compounds has been accomplished. The approach features simple treatment of the key intermediate with a Brønsted base to afford the tetracyclic cage-shaped target in one pot through a four-step domino transformation (see scheme; Mc = monochloromesylate, MOM = methoxymethyl).