Aflatoxin , general structure

Consideration of the generalized aflatoxin structure represented in (I) leads one to the inescapable conclusion that at the core of the system is the A-ring in the form of a phloroglucinol nucleus, in which each of the pendant phenolic oxygen atoms is uniquely differentiated. Furthermore, two of the three carbon sites on this nucleus are differentially substitued with carbon moieties. This constitutes a potentially difficult synthetic circumstance in that not only must a high degree of substitution be provided for, but also a certain amount of regiochemical control must... 

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