Aspergillus variecolor

In vitro studies of the ring closure reaction on closely related xanthone models result in a c/s-orientation of the hydroxyl and isopropenyl substituents which can be explained by steric clash between the ketone and xanthone carbonyls in the potential intermediate (10) which can be avoided if the ene reaction occurs on the benzophenone intermediate (9). This observation was supported by the isolation of previously known Aspergillus rugulosus metabolites, e.g. arugosin A (12), as co-metabolites of tajixanthone in Aspergillus variecolor. The involvement of anthraquinone intermediates was subsequently... 

In marked contrast to ravenelin and tajixanthone, no randomisation of [1, 2- 2] acetate labelling was observed on incorporation into sterigmatocystin (20) in Aspergillus variecolor, ruling out the involvement of a proposed symmetrical benzophenone intermediate [17]. 

Andibenin A (5.172) and andilesin A (5.173), which were isolated from a strain of Aspergillus variecolor, are examples of these more complex structures. The structures were established by a combination of spectroscopic and X-ray crystallographic studies. 

Andibenin B (117) is a highly oxidized meroterpenoid produced by the fungus Aspergillus variecolor. On the basis of the biosynthetic study,it was proposed that a plausible intermediate 115 from Claisen rearrangement of 114 affords the adduct 116 via the intramolecular inverse-electron demand [4 - - 2] cycloaddition as shown in Scheme 19(b). In this case, an enzyme catalyzes the cyclization of the terpene part on intermediate 114 derived from farnesyl diphosphate, and benzoates might provide the reactive dienophile 116. 

Aspergillus ustus Aspergillus variecolor Penicillium diversum Emericella denlata... 

Tajixanthone was isolated from cultures of Aspergillus stellatus in 1970, and it was proposed the structure 153 [178]. Subsequently, the structure was revised to the correct one, 154 [179]. The same xanthone derivative was also isolated from Aspergillus variecolor, and the structure 154 was confirmed with the 5-configuration assigned for C-15 and C-20 and R-configuration for C-25 (Figure 3.51) [180]. 

A new metabolite of Aspergillus variecolor, called anditomin, has been... 

Use of Long Range Proton-Carbon-13 Couplings in Structure Determination. Stellatin, a Novel Dihydrisocoumarin from Aspergillus variecolor. Chem. Commun. 1978, 627. 

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