Isolation and structural elucidation of novel fusicoccan dehydroxypericonicin A from Roussoella sp.

A potent antifungal fusicoccane dehydroxypericonicin A (1) was isolated from Roussoella sp. along with known allantofuranone (2). The relative structure of 1 was fully elucidated by NMR spectroscopic manner. The suggested relative structure was confirmed by density functional theory (DFT)-based 13C NMR chemical shift calculations. The absolute configuration was investigated by a spectral comparison of the experimental electronic circular dichroism spectrum with that based on the DFT calculations.