Total Synthesis of Callyspongiolide: An Anticancer Marine Natural Product

[Image: see text] The stereoselective total synthesis of cytotoxic marine macrolide callyspongiolide has been reported. The 14-membered macrolactone ring along with Z-olefin in the molecule was constructed via an intramolecular Horner–Wadsworth–Emmons olefination in a Z-selective fashion. The other E-olefinic moiety as well as the C9 stereocenter was introduced via stereoselective addition of the methyl group in an S(N)2′ fashion. The C5 stereocenter was installed via Sakurai allylation, whereas the C7 center was fixed by Jacobsen hydrolytic kinetic resolution. The C12 methyl and C13 hydroxy centers were fixed via Macmillan coupling reaction. The macrolactone core with a vinyl iodide side chain was coupled with the known alkyne fragment to complete the synthesis.