Synthesis of the C11-C29 fragment of amphidinolide F

reaction: see text] An efficient synthesis of the C(11)-C(29) fragment 31 of amphidinolide F has been accomplished via a diastereoselective 3 + 2]-annulation reaction of allylsilane 5 and ethyl glyoxylate to prepare the key tetrahydrofuran 15 and a highly stereoselective methyl ketone aldol reaction to generate the C(11)-C(16) segment.