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

The racemic form of the bicyclic diterpene hydrocarbon delta-araneosene (4), endowed with the dolabellane skeleton, was prepared from geraniol in two different ways. The more efficient route involved 13 steps and proceeded with an overall yield of 3.6% (average: 77% per step). with this reference sample at hand, the hitherto elusive metabolite (-)-4, a likely biogenetic precursor of cycloaraneosene ((-)-3) and sordaricin ((-)-1), could finally be isolated in greater than or equal to 99.5% purity from the neutral fractions of the mold Sordaria araneosa CAIN (Ascomycetes).