Stereocontrolled total synthesis of (+)-leucascandrolide A

Apparently no longer available from its natural source is the potent cytotoxic and antifungal agent leucascandrolide A (1), which was initially isolated from a New Caledonian calcareous sponge. A highly stereocontrolled total synthesis of this structurally unique macrolide commences with a Jacobsen asymmetric hetero Diels-Alder reaction to configure the tetrahydropyran ring. An efficient endgame relies on two Mitsunobu reactions, the first to generate the 18-membered macrolactone and the second to attach the oxazole-bearing side chain.