Synthesis of the Dolabellane Diterpene Hydrocarbon (±)‐δ‐araneosene

The racemic form of the bicyclic diterpene hydrocarbon δ‐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 ≥ 99.5% purity from the neutral fractions of the mold Sordaria araneosa CAIN (Ascomycetes).