On the stereostructures of (+)-eupenoxide and (−)-3′,4′-dihydrophomoxide: a caveat on the spectral comparisons of oxygenated cyclohexenoids

The structural ambiguity surrounding the structure of eupenoxide has been clarified and the absolute configuration of this natural product has been assigned. It is firmly established that ‘eupenoxide’ recently reported by Liu et al. is in fact a new natural product, (−)-3′,4′-dihydrophomoxide. The NMR spectra of these polyoxygenated cyclohexenoids exhibit subtle solvent, concentration, and temperature dependent variations, and due caution should be exercised when making spectral comparisons for structural assignments.