Efficient stereochemical relay en route to leucascandrolide A.

[structure: see text]. A complete relay of the initial stereochemical information is central to the efficient and highly stereocontrolled construction of the C1-C15 fragment of the marine macrolide leucascandrolide A. Cyclic silane 3, assembled via Pt-catalyzed hydrosilylation, was designed to serve as a temporary template for the installation of the C12 stereogenic center. The strategy features a highly convergent C10-C11 bond construction via 1,5-anti-selective aldol reaction and rapid assembly of the trisubstituted pyran subunit via Prins desymmetrization.