Stereoselective Synthesis of the Published Structure of Feigrisolide A. Structural Revision of Feigrisolides A and B

The total synthesis of the proposed structure of feigrisolide A is reported. Ethyl (S)-3-hydroxybutyrate was the chiral starting material. A Brown asymmetric allylation and an Evans aldol reaction were key steps of the synthesis. The NMR data of the synthetic product are different from those of the natural product. The published structure of feigrisolide A is therefore erroneous. A subsequent comparison of spectral data strongly suggests that feigrisolides A and B are identical with (−)-nonactic acid and (+)-homononactic acid, respectively.