Synthesis of Tronocarpine Framework via a Michael/Lactamization/Michael Cascade Process: Synthesis of Dihydrotronocarpine

This paper describes an efficient strategy that uses a Michael/lactamization/Michael one-pot cascade process to construct the pentacyclic core of tronocarpine. This key transformation used a seven-membered lactam derived from tryptamine and a Michael double acceptor to produce an advanced intermediate with all of the necessary functional groups to synthesize the natural product in 53% yield. Dihydrotronocarpine was then synthesized from this intermediate in two additional steps.