Non-Isoprenoid Monoterpenoids

Non-Isoprenoid Monoterpenoids.—There has been activity in the field of monoterpenoids formally related to chrysanthemic acid (43) and belonging to the odd artemesyl (44), santolenyl (45), and lavandulyl (46) groups where the customary head-to-tail linkage of isoprene units is not followed. Yomogi alcohol (47), the allylically rearranged artemisia alcohol (51), has been isolated from Artemisia feddei. The santolinyl class now includes two alcohols. 

Bessifere-Chrdtien, L. Peyron, L. B6n6zet, and J. Garnero, Bull. Soc. chim. France, 

Synthesis of yomogi alcohol (47) was achieved by sensitised photo-oxidation of the hydrocarbon (61) obtained by the Wurtz coupling (using magnesium) of 3-methylbut-2-enyl chloride (60). It has also been made from the known  

2-dimethylbut-3-enal using a Wittig reaction the latter publication also reports a synthesis of the structure (62), at one time believed to represent yomogi alcohol s  

Researches on chrysanthemic acid and its derivatives are usually oriented to synthesising esters of trans-chrysanthemic acid, many of which are naturally occurring (and are, therefore, presumably biodegradable) insecticides. The synthesis of pyrethric acid or its mono-ester (65) from chrysanthemic acid has been carried out in two laboratories. Ueda and Matsui prepared all four 

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Dimethylethylcydohexanes.—Two new halogenated monoterpenoids are violacene (150) from Plocamium violaceum,250 a 1,4-dimethyl-1-ethylcyclohexane which can be rationalized biosynthetically from the cyclization of an acyclic precursor via a bromonium ion, and plocamene B (151), again from Plocamium violaceum, which may be the first member of a series of non-isoprenoid monoterpenoids from this species.251... 

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