Discrepancy of the spectral data between adunctin E and the synthetic one

Compound (2), which has been proposed as the structure of adunctin E (1), was prepared in nine steps in 17% overall yield from hexahydrodibenzofuranone (4); however, the spectral data of this compound, including 1H and 13C NMR spectra, were inconsistent with the literature data for adunctin E (1). Thus, we suggest that the proposed structure for adunctin E or the reported NMR spectral data was incorrect.