Studies Directed toward the Stereoselective Synthesis of Cytospolide E

Our exhaustive effort toward the total synthesis of cytotoxic marine nonanolide cytospolide E has been detailed. To achieve this synthesis, we have explored both the ring-closing metathesis and lactonization-based macrocyclization strategies using a variety of precursors. Unfortunately, none of them provided the desired product. The ring-closing metathesis approach provided mainly the macrocycle with Z-olefin, whereas the macrolactonization strategy culminated in 8-epi-9-epi-cytospolide E following the regioselective formation of a 10-membered macrocycle over a 9-membered macrocycle.