Biogenesis Diels-Alder reaction

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... 

Vosburg DA, Vanderwal CD, Sorensen EJ (2002) A synthesis of (+)-FRl 82877, featuring tandem transannular Diels-Alder reactions inspired by a postulated biogenesis. J Am Chem Soc 124 4552- 553... 

Mander and Thomson reported the total synthesis of sordaricin (120), a diterpene isolated from the ascomycete Sordaria araneosa Cain (Scheme 8.19) [51]. Inspired by its biogenesis, they devised a synthetic plan involving a domino retro Diels-Alder/IMDA reaction of a mask cyclopentene 121. Upon liberation of cyclopentene, intermediate 122 underwent an IMDA reaction to give the desired sordaricin analog 123 along with a minor cycloaddnct regioadduct 124. 

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