Total\nSyntheses of Scabrolide B, Ineleganolide, and\nRelated Norcembranoids

Concise total syntheses of several\n5/7/6 norcembranoids, including\nineleganolide, scabrolide B, sinuscalide C, and fragilolide A have\nbeen achieved through a fragment coupling/ring closure approach. The\ncentral seven-membered ring was forged through sequential Mukaiyama–Michael/aldol\nreactions using norcarvone and a decorated bicyclic lactone incorporating\na latent electrophile. Subsequent manipulations installed the reactive\nenedione motif and delivered scabrolide B in 11 steps from a chiral\npool-derived enone. Finally, ineleganolide, sinuscalide C, and fragilolide\nA were each accessed in one additional step.