Abstract
Three pairs of new isopentenyl dibenzo[b,e]oxepinone enantiomers, (+)-(5S)-arugosin K (1a), (−)-(5R)-arugosin K (1b), (+)-(5S)-arugosin L (2a), (−)-(5R)-arugosin L (2b), (+)-(5S)-arugosin M (3a), (−)-(5R)-arugosin M (3b), and a new isopentenyl dibenzo[b,e]oxepinone, arugosin N (4), were isolated from a wetland soil-derived fungus Talaromyces flavus, along with two known biosynthetically-related compounds 5 and 6. Among them, arugosin N (4) and 1,6,10-trihydroxy-8-methyl-2-(3-methyl-2-butenyl)-dibenz[b,e]oxepin-11(6H)-one (CAS: 160585-91-1, 5) were obtained as the tautomeric mixtures. The structures of isolated compounds were determined by detailed spectroscopic analysis. In addition, the absolute configurations of these three pairs of new enantiomers were determined by quantum chemical ECD calculations.
Highlights
Isopentenyl dibenzo[b,e]oxepinones possess a dibenzo[b,e]oxepin-11(6H)-one skeleton with isopentenyl substitution
About nine isopentenyl dibenzo[b,e] oxepinones had been reported from fungi in Nature, including arugosins A–D from Aspergillus rugulosus [1,2]
In our search for bioactive secondary metabolites from wetland fungi [10,11,12,13,14,15], several interesting molecules had been isolated from this species [12,13,14,15]
Summary
Isopentenyl dibenzo[b,e]oxepinones possess a dibenzo[b,e]oxepin-11(6H)-one skeleton (intact 6-7-6 tricyclic system) with isopentenyl substitution. About nine isopentenyl dibenzo[b,e] oxepinones had been reported from fungi in Nature, including arugosins A–D from Aspergillus rugulosus [1,2]. Acristata [4], pestalachloride B from Pestalotiopsis adusta [5], cephalanones D–E from Graphiopsis chlorocephala [6], and 1,6,10trihydroxy-8-methyl-2-(3-methyl-2-butenyl)-dibenz[b,e]oxepin-11(6H)-one (CAS: 160585-91-1, 5) from. A chemical investigation of metabolites from Talaromyces flavus AHK07-3 was carried out, which led to the isolation of three pairs of new isopentenyl dibenzo[b,e]oxepinone enantiomers ((+)-(5S)-arugosin K. The absolute configurations of the three pairs of enantiomers were (5). 1,6,10-trihydroxy8-methyl-2-(3-methyl-2-butenyl)-dibenz[b,e]oxepin-11(6H)-one (5) were a pair of tautomers, and they. 8-methyl-2-(3-methyl-2-butenyl)-dibenz[b,e]oxepin-11(6H)-one (5)elucidations were a pair of and were isolated as mixtures.
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