Penifulvin A: A Sesquiterpenoid-Derived Metabolite Containing a Novel Dioxa[5,5,5,6]fenestrane Ring System from a Fungicolous Isolate of <i>Penicillium</i> <i>g</i><i>riseofulvum</i>

Penifulvin A (1), a new fungal metabolite with a previously undescribed ring system, has been isolated from cultures of an isolate of Penicillium griseofulvum (NRRL 35584) obtained from a white mycelial growth on a dead hardwood branch collected in a Hawaiian forest. The structure was assigned by analysis of NMR data and confirmed by single-crystal X-ray diffraction analysis. Penifulvin A (1) shows significant activity in dietary assays against the fall armyworm Spodoptera frugiperda.