Synthetic Studies Concerned with the Proposed Structure of Ribisin F, a Compound with Nerve Growth Factor Potentiating Activity Isolated from the Medicinal Fungus Phellinus ribis

The synthesis of the enantiomer of the structure assigned to the title natural product has been achieved from abundant quinic acid. However, the NMR spectral data acquired on the synthetic material do not match those reported for ribisin F (which are of rather modest quality). In an effort to establish the true structure of ribisin F, an epimer of the assigned structure was also prepared from quinic acid. A comparison of the spectral data obtained on this epimer with those reported for the natural product proved a better match and based on optical rotation data the possible true structure of this distinctive, dihydroxylated and benzofuran-containing compound is tentatively proposed.