Cyclotrimerization Strategy toward Analogues of Amaryllidaceae Constituents. Synthesis of Deoxygenated Pancratistatin Core

[chemical reaction: see text]. A derivative of pancratistatin having no oxygenation in the aromatic ring was synthesized by a new strategy based on the cobalt-catalyzed cyclotrimerization of acetylenes as a prelude to diversity-oriented synthesis of further analogues.