Synthesis and Structure Revision of the C43–C67 Part of Amphidinol 3

Stereoselective synthesis of the C43–C67 part of amphidinol 3 (AM3) and its C51-epimer was achieved starting from a common intermediate corresponding to the tetrahydropyran moiety of AM3, via asymmetric oxidations and Julia–Kocienski olefination. By comparing NMR data of the synthetic specimens with those of AM3, the absolute configuration at C51 of AM3 was revised from <i>R</i> to <i>S</i>