Synthesis of the C-18-C-34 fragment of amphidinolides C, C2, and C3.

The C-18-C-34 fragment of amphidinolides C, C2, and C3 and the C-18-C-29 fragment of amphidinolide F have been constructed from a trans-2,5-disubstituted dihydrofuran. This key intermediate was prepared from a dihydrofuranone formed by diastereoselective rearrangement of a free or metal-bound oxonium ylide generated from a metal carbenoid. The side chains found in amphidinolides C and F were introduced using Sonogashira coupling reactions.