An efficient and stereoselective synthesis of the monomeric counterpart of marinomycin A.

[structure: see text] The monomeric counterpart of marinomycin A, an antitumor-antibiotic marine natural product, was synthesized efficiently in 11 steps from the commercially available ethyl (R)-(-)-3-hydroxybutyrate. The strategy was highlighted by a crucial regio- and stereoselective cross-metathesis to form the C20-C21 double bond, enantioselective allyltitanations to control the configuration of the C17, C23, and C25 stereogenic centers, and a stereocontrolled construction of the tetraene moiety based on an original Horner-Wadsworth-Emmons olefination followed by a Pd-catalyzed cross-coupling.