The sesquiterpene fraction of the essential oil ofArtemisia laciniata Willd.

The sesquiterpene fraction of the essential oil from Artemisia laciniata Willd. (Compositae) from the Kashmir region of India was analysed and found to contain mainly oxygenated derivatives. The main constituent, about 4% of the total oil, is silphiperfol-5-en-3-ol A (29). Besides many other minor compounds possessing this rare skeleton, the biogenetically related presilphiperfolan-9α-ol (17, ca. 2%) was isolated. Almost all the other compounds represent the davanones (21, 27, 32) and their oxygenated derivatives (23, 36, 37, 40). Most important are the bicyclic artedouglasia oxides (13, 15, 24, 30) and the laciniatafuranones (12, 14, 16, 19, 20). Five of the eight possible diastereoisomers of this novel compound were isolated and stereochemically assigned by extensive 2H-NMR studies and molecular modelling considerations. Two compounds, the 3-hydroxyisodavonone (23) and its 1,2-dehydro derivative (37) show a unique keto enol moiety. Presilphiperfolan-9-ol (17, woody, sweet) and silphiperfol-5-en-3-ol A (29, woody, ambergris) contribute remarkably to the interesting odour of this Artemisia oil.