Formal Total Synthesis of Amphidinolide E

A formal total synthesis of the cytotoxic macrolide amphidinolide E is reported. The strategic steps are three Julia–Kocienski reactions (J–K), for the formation of the C5–C6, C9–C10, and C17–C18 double bonds, a Suzuki–Molander C21–C22 bond formation reaction, and a Kita–Trost macrolactonization. The “instability” of the two dienic systems and of the stereocenter at C2 (allylic methine, α to the carboxy group) and the protecting groups at C17-OH and C18-OH have posed difficult challenges. Each Julia–Kocienski olefination has been systematically optimized to provide the highest possible E/Z ratios.