Two benzaldehyde derivatives and their artefacts from a gorgonian-derived Eurotium sp fungus

Two new benzaldehyde derivatives, named 3-OH-tetrahydroauroglaucin (1) and(3S*,4R*)-6-(3,5-epoxy-4-hydroxy-1-heptenyl)-2-hydroxy-3-(3-methyl-2-butenyl)benzaldehyde (2), were isolated from a gorgonian-derived Eurotium sp. fungus. Their structures were determined by extensive spectroscopic analysis including NMR and MS spectra. Dissolved 1 in CDCl3 for several days could be detected its 2H-chromene skeleton derivatives (1a/1b), a pair of enantiomers with opposite configurations at C-3. Compound 2 was also found to chemically convert to a pair of epimers non-enzymatically. The plausible mechanism to form the 2H-chromene artefacts with racemisation at C-3 undergoing nucleophilic substitution (S(N)1) was proposed. [GRAPHICS] .