“…Very few compounds are known that fall into this class of highly cyclised terpenes, including the tricyclic monoterpene ( n =2) cyclofenchene ( 1 ), [3] the tetracyclic sesquiterpenes ( n =3) longicyclene ( 2 ), [4] cyclosativene ( 3 ), [5] ishwarane ( 4 ), [6] cycloseychellene ( 5 ), [7] and cyclomyltaylane ( 6 ), [8] and the pentacyclic diterpene ( n =4) trachylobane ( 7 ) [9,10] . The related compound helifulvane ( 8 ) is the hypothetical parent hydrocarbon to a number of oxidised derivatives [11] . Despite the discovery of these compounds several decades or even more than 100 years ago, so far no hexacyclic sesterterpene hydrocarbons as direct terpene synthase products are known, while hexacyclic oxidised derivatives, such as the niduterpenoids A and B from Aspergillus nidulans , have been isolated [12] .…”