SYNTHESIS OF THE DOLABELLANE DITERPENE HYDROCARBON (+ -)-DELTA-ARANEOSENE/

The racemic form of the bicyclic diterpene hydrocarbon delta-araneosen e (4), endowed with the dolabellane skeleton, was prepared from gerani ol in two different ways. The more efficient route involved 13 steps a nd proceeded with an overall yield of 3.6% (average: 77% per step). wi th this reference sample at hand, the hitherto elusive metabolite (-)- 4, a likely biogenetic precursor of cycloaraneosene ((-)-3) and sordar icin ((-)-1), could finally be isolated in greater than or equal to 99 .5% purity from the neutral fractions of the mold Sordaria araneosa CA IN (Ascomycetes).