Penicillium diversum

The labelling studies described above provide definitive evidence for the mixed polyketide-terpenoid biogenesis of the andibenins, andilesins, andi-tomins, austin and terretonin. The formation of the bicyclo [2.2.2] octane system in the first two classes of metabolite provides a rare example of a biosynthetic Diels-Alder reaction. The biosynthetic relationship of austin and andibenin was supported by the isolation of austin from another mutant strain of A. variecolor [81]. Further metabolites related to austin have been isolated from Emericella dentata [82] and Penicillium diversum [81]. Other complex metabolites which are almost certainly further products of the meroterpenoid pathway are fumiga-tonin (102) and paraherquonin (103) which have been isolated from Aspergillus... 

Aspergillus ustus Aspergillus variecolor Penicillium diversum Emericella denlata... 

Diversonol (97), a fungal metabolite, was isolated by Turner from Penicillium diversum and its structural motif has also been found in some mycotoxins such as secalonic acids with interesting biological activity. Therefore, the total synthesis of diversonol will also promote the total synthesis of these... 

In 1978, Turner reported the isolation of several fungal metabolites, including a compound from the phenolic fraction of cultured Penicillium diversum that was named subsequently diversonol (932) 642). It was not made clear in the initial publication if diversonol (932) was obtained as a racemate or, if this was not the case, the absolute configuration. Mention was made in this initial publication to X-ray crystallographic data that were to be reported later, but it evidently such work did not come to completion (Fig. 13.12). 

In 1983 Holker, Simpson, and O Brien reported the isolation of the diversonolic esters (972, 973) (Fig. 13.15), which they obtained from Penicillium diversum, along with lichexanthone (840a) and several other known compounds (634). The authors performed a structural analysis for these new compounds based on methyl-ation, proton-NMR analysis, chelate ferric effects, and other spectroscopic techniques, which led to the assignment of the structures of these new compounds as 970 and 971. These substances appear reminiscent of hemisecalOTiic acids (ergochrome monomers), but the structures originally proposed were later found to be incorrect (see below). 

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