Coupling of Alkenes and Alkynes: Synthesis of the C1−C11 and C18−C28 Fragments of Miyakolide

A transition metal-mediated, atom-economical approach toward the crucial A and D rings of miyakolide is described. A Pd-catalyzed alkyne−alkyne coupling/6-endo-dig cyclization is employed to assemble the A ring fragment. The key D ring pyran is constructed utilizing an Ru-catalyzed alkene−alkyne coupling followed by a Pd-catalyzed allylic alkylation to establish the all-cis stereochemistry.