2-epi-a-cedrene

It is clear from these and previous results obtained over the past two or three years that the spiro-sesquiterpenes provide an important link between certain monocyclic and tricyclic sesquiterpenes. This is further exemplified by the recent work of Andersen and SyrdaP who have now reappraised the absolute stereochemistries of (-)-a- (137) and (- )-/3-alaskene (138). It now appears that 5-acoradiene, isolated by Hirose et is, in fact, (-I-)- -alaskene. Andersen and Syrdal also made the interesting observation that phthalic anhydride dehydration of the diols derived from iso-acorone (139) gave rise to small amounts of (-f )-a-cedrene (126 R = Me) and (— )-2-epi-a-cedrene (136). Subsequently these authors found that (-t- )-nerolidol (140) and a number of its derivatives undergo acid-catalysed cyclization to a mixture of a- and -bisabolenes (141), of which the... 

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