The total synthesis of methyl sarcophytoate (1), a marine natural biscembranoid, has been achieved by the thermalDiels−Alderreaction between the 14-membered dienophile unit, methyl sarcoate (2), and the 14-membered diene unit 64. Methyl sarcoate (2) was prepared using n-BuLi-Bu2Mg-mediated dithiane coupling, Kosugi−Migita−Stille coupling, and Grubbs ring-closing metathesis. The diene unit 64 was