Total synthesis of (-)-exiguolide.

Total synthesis of (-)-exiguolide, the natural enantiomer, has been accomplished for the first time. The bis(tetrahydropyran) subunit was efficiently synthesized via consecutive olefin cross-metathesis/intramolecular oxa-conjugate addition/reductive etherification. Construction of the 20-membered macrocycle was achieved by Yamaguchi macrolactonization. Stereoselective introduction of the (E,Z,E)-triene side chain via Suzuki-Miyaura coupling completed the total synthesis.