Total Syntheses of (±)‐Fawcettimine, (±)‐Fawcettidine, (±)‐Lycoflexine,and (±)‐Lycoposerramine‐Q

The total syntheses of four fawcettimine‐related Lycopodium alkaloids, (±)‐fawcettimine, (±)‐fawcettidine, (±)‐lycoposerramine‐Q, and (±)‐lycoflexine, were completed in a highly stereoselective manner. The Pauson–Khand reaction of 4‐methylidene‐6‐siloxyoct‐1‐en‐7‐yne followed by regio‐ and stereoselective hydrogenation led to the short‐step preparation of the bicyclo4.3.0]nonenone intermediate bearing a methyl group with the required stereochemistry. The subsequent chemical manipulation of the bicyclic compound afforded the 6‐5‐9‐membered tricyclic dioxo compound, which was then transformed into the four targeted alkaloids in an alternative and more efficient fashion.