NMR Spectroscopic Method for the Assignment of 3,5-Dioxygenated Aromatic Rings in Natural Products

In recent years, certain “new” naturally occurring compounds (1–28) with 3,5-dioxygenated aromatic rings have been reported. A comparison of the NMR data of these compounds with the data of four model compounds (A–D) indicated that the structures of these “new” compounds were erroneous. The reason for the incorrect elucidation of the structures of 1–28 was attributed to “deceptively simple” 1H NMR spectra, which displayed two broad singlets with...