Cubebanes

Reactions.—3-Isopropylcyclopent-2-en-l-one reacted with Me-SOl-NaH to give sabina ketone and sabinene oxide 619 the latter could be cleaved to p-menthan-1-ol.620 Thujone and isothujone (for nomenclature see ref. 59) coupled with methyl vinyl ketone under basic conditions to give an adduct that could be modified to sesquithujane (e.g. cubebane) derivatives.621 (—)-Isothujone with HCHO formed the 1-hydroxymethyl derivative that underwent Jones oxidation and decarboxylation to (+)-thujone.622 623... 

Cadinane, Cubebane, Oplopanane, Picrotoxane, Sativane, Copacamphane... 

Three independent syntheses of the cubebane-type skeleton have been reported in which formation of the cyclopropane ring was once again achieved by an internal diazoketone cyclisation. In the first of these syntheses, Yoshikoshi et utilised (—)-trans-caran-2-one as the starting material which was converted in three steps to the spiro-lactone (83). Pyrolytic rearrangement of this compound to the key olefin-acid (84) was accomplished in 70% yield. Conversion to the corresponding diazoketone, followed by decomposition yielded the tricyclic ketone (85, R = O) and its stereoisomer (86). Standard procedures converted... 

Cubebanes and ivaxillaranes represent 1,6- and 8,10-cycloguaianes, respectively. The fruits of Java pepper Piper cubeba (Piperaceae) contain (-)-4-cubebanol. The name ivaxillarane stems from Iva axillaris with (-)-ivaxillarin as a constituent. 

Cubebane type (Fig. 8.1.13) sesquiterpenoids have a very restricted distribution and have not been, so far, found in woody tissues. 

Chart 11. Chamigrane, copaanes, ylanganes, and cubebanes found in the Hepaticae... 

---