Total synthesis of jerangolid A.

The first total synthesis of the antifungal polyketide jerangolid A has been accomplished. Starting with the readily available (R)-Roche ester and (S)-glycidol as chirons, the synthesis involved a highly syn-selective Lewis acid catalyzed 6-endo-trig cyclization for the construction of the dihydropyran subunit. The lactone segment was built through a tandem NaOMe conjugate addition-lactonization reaction, and further functionalized through a sequence consisting of iodination, I-Mg exchange, and hydroxymethylation. Other key steps in the synthesis featured a novel application of a phosphonamide-anion based olefination and a Julia-Kocienski reaction.