Structural incongruities of coleophomone natural products: insights by total synthesis of a semi-synthetic derivative

An unexpected structural incongruity between coleophomones 1 and the reported structure of recently isolated natural product 2 was confirmed by total synthesis of key semi-synthetic derivative 3 and its positional isomer 4. In addition, possible mechanisms for the interconversion of expected structure 22 to observed compound 2 are postulated, some of which may have an important role in the biosynthetic origin and chemistry of these structurally unique natural products.