Stereodivergent synthesis and relative stereostructure of the C1-C13 fragment of symbiodinolide

Four possible diastereomers of the C1-C13 fragment of symbiodinolide, which were proposed by the stereostructural analysis of the degraded product, were synthesized in a stereodivergent and stereoselective manner. The key transformations were aldol reaction of methyl acetoacetate with the aldehyde, diastereoselective reduction of the resulting β-hydroxy ketone, and the stereoinversion at the C6 position. Comparison of the ¹H NMR data between the four synthetic products and the degraded product revealed the relative stereostructure of the C1-C13 fragment of symbiodinolide.