Synthesis of the C3−C18 Fragment of Amphidinolides G and H

A synthesis of an amphidinolides G and H C3−C18 subunits is reported. The C10−C18 segment 4 was prepared by a Negishi cross-coupling, whereas the synthesis of the C3−C9 fragment 5 employed an asymmetric cyanosilylation as the key step. The two segments were coupled by lithiation of iodide 4 and trapping of the anion with amide 5. The allylic epoxide moiety could be synthesized from the protected anti- mesylate 22.