The absoluteconfiguration of cuauhtemone and related compounds

The absoluteconfiguration of cuauhtemone, a eudesmane-type sesquiterpene isolated from Pluchea species (Asteraceae), has been revised from 1 to 2 by chemical correlation with (R)-(+)-2-methyl-1,2-butanediol 3 through the naturally occurring 2,3-epoxy-2-methylbutanoate derivative 4. The relative stereochemistry of 4 was confirmed by X-ray diffraction analysis. The obtained data are also useful for reconsideration of the absoluteconfigurations of a relevant group of natural products, which were elucidated according to the stereochemistry of cuauhtemone.