1H NMR Reassignment for Z/E-Benzomalvins B and Absolute Configuration of Benzomalvin C

Benzomalvins B, C, and E (1, 2, and 3) were simultaneously obtained from the marine fungus Aspergillus sp. isolated from the soft coral Sinularia sp., collected from South China Sea. Their structures were elucidated on the basis of NMR spectroscopic data and by comprehensive comparison with those previously reported in the literature. The stability of the double bond of E-benzomalvin B (1) under different light conditions was investigated, and 1 was transformed to Z-benzomalvin B (1′) with UV 365 nm irradiation. In particular, the incorrect 1H NMR data of 1′ in the literature was reassigned for the first time. Moreover, the absolute configuration of benzomalvin C (2) was also reported for the first time by X-ray single crystal diffraction.