Total Syntheses of (−)-Macrolactin A, (+)-Macrolactin E, and (−)-Macrolactinic Acid:  An Exercise in Stille Cross-Coupling Chemistry

The total syntheses of the potent antiviral agent (−)-macrolactin A (1) and two related family members, (+)-macrolactin E (5) and (−)-macrolactinic acid (7), have been achieved, exploiting a unified, convergent, and highly stereocontrolled strategy. Extensive use of the palladium-catalyzed Stille cross-coupling reaction for the stereospecific construction of the three isolated dienes including macrocyclization formed the cornerstone of the successful strategy. The total syntheses of these natural products, no longer available via fermentation, confirm their relative and absolute stereochemistries and provide access to possible analogues for further biological study.