by

carbon skeleton (4). This linearly-fused tricyclic system ltriquinane) is present in many
sesquiterpenes which possess the hirsutane (5) and capnellane (6) structures.
5
4
The three rings in both compounds are fused in the most thermodynamically stable
cis-anti-cis configuration. The main difference between the two isomers is in the
regiochemistry of the angular and geminal methyl groups. The various triquinane
sesquiterpenes differ in the number and position of oxygen atoms in the molecule.
Hirsutene (7).16 the parent hydrocarbon of the hirsutane-like sesquiterpenes has
received much attention as a target in the synthesis of linearly fused cyclopentanoids. 17
The most important members of the hirsutane-like sesquiterpenes are the
coriolins ll (8- 1 1). Coriolin (8) was isolated from the culture broth of a Basidiomycetous
fungus Corio/us consors in 1969. and its structure was elucidated two yaars later by
Takahashi and co-workers. 19
Diketocoriolin (10), the oxidation product of coriolin 8 (9) has antifungal and
antlmicrobial properties. Modification of the ester groups led to no loss of biological
activity.10 Kunimoto and Umezawa observed that the mode of action of diketocoriolin 8 on
mammalian cells involved inhibition of Na-K-ATPase. 31
6
6