Synthesis of four diastereomers of the C1-C12 fragment of amphirionin-5 has been achieved in a convergent and stereodivergent manner. Detailed comparison of the (1)H and (13)C NMR data of each compound with those reported for the natural product led to not only the stereochemical assignment of the relative configuration of the C4/C5 stereogenic centers but also reassignment of the proposed relative configuration at C9 of amphirionin-5.

The relative configuration of the C3-C12 portion of amphirionin-5, a novel marine polyketide with potent cell proliferation-promoting activity, was established by the stereodivergent synthesis of six diastereomeric model compounds and comparison of their NMR spectroscopic data with those reported for the natural product. This study led to the elucidation of the relative configuration between C4/C5 and C9/C12 and to the reassignment of the proposed configuration of the C9 position of amphirionin-5.