Asymmetric Total Synthesis of (+)-Mannolide C

(+)-Mannolide C is a complex hexacyclic C 20 cephalotane-type diterpenoid featuring a highly strained 7/6/6/5 tetracyclic core embedded with eight consecutive stereocenters and two bridging lactones. The first asymmetric total synthesis of (+)-mannolide C has been accomplished by lipase-mediated resolution, Ru-complex-catalyzed double ring-closing metathesis (RCM) reactions, Ni(II)-catalyzed diastereoselective Michael addition, and Mn(III)-catalyzed allylic oxidation as the key transformations.