Seco-illudanes

Full details of the previously reported (Vol. 6, p. 73) synthesis of the seco-illudane sequiterpenoid hypacrone (346) have been published. An interesting feature of the synthetic route is the use of a directed crossed aldol condensation between the diketone (344) and the trimethylsilyl enol-ether (343) to produce the trans-isomer (345) of hypacrone (346). The absolute configuration of fomannosin (347) has finally been established by X-ray analysis of the camphanate ester derivative (348). Full details of the biosynthesis of fomannosin (347) from [l,2- C2]acetate (c/. Vol. 7, pp. 82, 196) have been published. The labelling pattern and couplings in fomannosin (347) are consistent with a biosyn-... 

The 1-indanone derivatives isolated from ferns are designated as pterosins and their glycosides as pterosides (SOS), Pterosins belong to the so-called illudalane type of sesquiterpenes which possess carbon skeleton 413. Illudalanes are seco-illudanes and illudanes possess carbon skeleton 414. 

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