A concise and convergent totalsynthesis of the highly cytotoxic marine natural products iejimalide A-D (1-4) is reported, which relies on an effective ring-closingmetathesis (RCM) reaction of a cyclization precursor containing no less than 10 double bonds. Because of the exceptional sensitivity of this polyunsaturated intermediate and its immediate precursors toward acid, base, and even gentle warming
member of a small family of marine polyenemacrolides endowed with remarkably selective activity against human cancer cell lines. As this product, however, is hardly available from the natural sources, a detailed evaluation requires the development of an efficient and practical synthetic approach. This challenge has now been met by adapting the first total synthesis of 2 previously reported by our group